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is-link">Go</button> </div> </div> </form> </div> </div> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.01990">arXiv:2406.01990</a> <span> [<a href="https://arxiv.org/pdf/2406.01990">pdf</a>, <a href="https://arxiv.org/format/2406.01990">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> 50 GeV $蟺^-$ in, nothing out: a sensitive probe of invisible $畏$ and $畏'$ decays with NA64h </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Antonov%2C+A">A. Antonov</a>, <a href="/search/hep-ex?searchtype=author&query=Torres%2C+M+A+A">M. A. Ayala Torres</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Oberhauser%2C+B+B">B. Banto Oberhauser</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bisio%2C+P">P. Bisio</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gertsenberger%2C+S+V">S. V. Gertsenberger</a>, <a href="/search/hep-ex?searchtype=author&query=Girod%2C+S">S. Girod</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Kambar%2C+Y">Y. Kambar</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G+D">G. D. Kekelidze</a> , et al. (32 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.01990v1-abstract-short" style="display: inline;"> We present the first results from a proof-of-concept search for dark sectors via invisible decays of pseudoscalar $畏$ and $畏'$ mesons in the NA64h experiment at the CERN SPS. Our novel technique uses the charge-exchange reaction of 50 GeV $蟺^-$ on nuclei of an active target as the source of neutral mesons. The $畏, 畏' \to invisible$ events would exhibit themselves via a striking signature - the com… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01990v1-abstract-full').style.display = 'inline'; document.getElementById('2406.01990v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.01990v1-abstract-full" style="display: none;"> We present the first results from a proof-of-concept search for dark sectors via invisible decays of pseudoscalar $畏$ and $畏'$ mesons in the NA64h experiment at the CERN SPS. Our novel technique uses the charge-exchange reaction of 50 GeV $蟺^-$ on nuclei of an active target as the source of neutral mesons. The $畏, 畏' \to invisible$ events would exhibit themselves via a striking signature - the complete disappearance of the incoming beam energy in the detector. No evidence for such events has been found with $2.9\times10^{9}$ pions on target accumulated during one day of data taking. This allows us to set a stringent limit on the branching ratio ${\rm Br}(畏' \to invisible) < 2.1 \times 10^{-4}$ improving the current bound by a factor of $\simeq3$. We also set a limit on ${\rm Br}(畏\to invisible) < 1.1 \times 10^{-4}$ comparable with the existing one. These results demonstrate the great potential of our approach and provide clear guidance on how to enhance and extend the sensitivity for dark sector physics from future searches for invisible neutral meson decays. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01990v1-abstract-full').style.display = 'none'; document.getElementById('2406.01990v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2024-153 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.06982">arXiv:2404.06982</a> <span> [<a href="https://arxiv.org/pdf/2404.06982">pdf</a>, <a href="https://arxiv.org/format/2404.06982">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> First constraints on the $L_渭-L_蟿$ explanation of the muon $g-2$ anomaly from NA64-$e$ at CERN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Antonov%2C+A">A. Antonov</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Oberhauser%2C+B+B">B. Banto Oberhauser</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bisio%2C+P">P. Bisio</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=H%C3%B6sgen%2C+M">M. H枚sgen</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Kambar%2C+Y">Y. Kambar</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a> , et al. (36 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.06982v6-abstract-short" style="display: inline;"> The inclusion of an additional $U(1)$ gauge $L_渭-L_蟿$ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light $Z^\prime$ vector boson, with dominant coupling to $渭$ and $蟿$ leptons and interacting with electrons via a loop mechanism. The $L_渭-L_蟿$ model can also explain the Dark Matte… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.06982v6-abstract-full').style.display = 'inline'; document.getElementById('2404.06982v6-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.06982v6-abstract-full" style="display: none;"> The inclusion of an additional $U(1)$ gauge $L_渭-L_蟿$ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light $Z^\prime$ vector boson, with dominant coupling to $渭$ and $蟿$ leptons and interacting with electrons via a loop mechanism. The $L_渭-L_蟿$ model can also explain the Dark Matter relic abundance, by assuming that the $Z'$ boson acts as a "portal" to a new Dark Sector of particles in Nature, not charged under known interactions. In this work we present the results of the $Z'$ search performed by the NA64-$e$ experiment at CERN SPS, that collected $\sim 9\times10^{11}$ 100 GeV electrons impinging on an active thick target. Despite the suppressed $Z'$ production yield with an electron beam, NA64-$e$ provides the first accelerator-based results excluding the $g-2$ preferred band of the $Z'$ parameter space in the 1 keV $ < m_{Z'} \lesssim 2$ MeV range, in complementarity with the limits recently obtained by the NA64-$渭$ experiment with a muon beam. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.06982v6-abstract-full').style.display = 'none'; document.getElementById('2404.06982v6-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 5 figures. New version with extended exclusion limits down to 1 keV in Z' mass</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2024-103 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.15612">arXiv:2308.15612</a> <span> [<a href="https://arxiv.org/pdf/2308.15612">pdf</a>, <a href="https://arxiv.org/format/2308.15612">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> </div> <p class="title is-5 mathjax"> Probing Light Dark Matter with positron beams at NA64 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Antonov%2C+A">A. Antonov</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Oberhauser%2C+B+B">B. Banto Oberhauser</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bisio%2C+P">P. Bisio</a>, <a href="/search/hep-ex?searchtype=author&query=Bondi%2C+M">M. Bondi</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Kambar%2C+Y">Y. Kambar</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a> , et al. (41 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.15612v1-abstract-short" style="display: inline;"> We present the results of a missing-energy search for Light Dark Matter which has a new interaction with ordinary matter transmitted by a vector boson, called dark photon $A^\prime$. For the first time, this search is performed with a positron beam by using the significantly enhanced production of $A^\prime$ in the resonant annihilation of positrons with atomic electrons of the target nuclei, foll… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.15612v1-abstract-full').style.display = 'inline'; document.getElementById('2308.15612v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.15612v1-abstract-full" style="display: none;"> We present the results of a missing-energy search for Light Dark Matter which has a new interaction with ordinary matter transmitted by a vector boson, called dark photon $A^\prime$. For the first time, this search is performed with a positron beam by using the significantly enhanced production of $A^\prime$ in the resonant annihilation of positrons with atomic electrons of the target nuclei, followed by the invisible decay of $A^\prime$ into dark matter. No events were found in the signal region with $(10.1 \pm 0.1)~\times~10^{9}$ positrons on target with 100 GeV energy. This allowed us to set new exclusion limits that, relative to the collected statistics, prove the power of this experimental technique. This measurement is a crucial first step toward a future exploration program with positron beams, whose estimated sensitivity is here presented. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.15612v1-abstract-full').style.display = 'none'; document.getElementById('2308.15612v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Version submitted to PRL</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2023-192 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.02404">arXiv:2307.02404</a> <span> [<a href="https://arxiv.org/pdf/2307.02404">pdf</a>, <a href="https://arxiv.org/format/2307.02404">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> Search for Light Dark Matter with NA64 at CERN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Oberhauser%2C+B+B">B. Banto Oberhauser</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bisio%2C+P">P. Bisio</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Silva%2C+R+B+G">R. B. Galleguillos Silva</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gertsenberger%2C+S+V">S. V. Gertsenberger</a>, <a href="/search/hep-ex?searchtype=author&query=Girod%2C+S">S. Girod</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=H%22osgen%2C+M">M. H"osgen</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Kambar%2C+Y">Y. Kambar</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a> , et al. (38 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.02404v1-abstract-short" style="display: inline;"> Thermal dark matter models with particle $蠂$ masses below the electroweak scale can provide an explanation for the observed relic dark matter density. This would imply the existence of a new feeble interaction between the dark and ordinary matter. We report on a new search for the sub-GeV $蠂$ production through the interaction mediated by a new vector boson, called the dark photon $A'$, in collisi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02404v1-abstract-full').style.display = 'inline'; document.getElementById('2307.02404v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.02404v1-abstract-full" style="display: none;"> Thermal dark matter models with particle $蠂$ masses below the electroweak scale can provide an explanation for the observed relic dark matter density. This would imply the existence of a new feeble interaction between the dark and ordinary matter. We report on a new search for the sub-GeV $蠂$ production through the interaction mediated by a new vector boson, called the dark photon $A'$, in collisions of 100 GeV electrons with the active target of the NA64 experiment at the CERN SPS. With $9.37\times10^{11}$ electrons on target collected during 2016-2022 runs NA64 probes for the first time the well-motivated region of parameter space of benchmark thermal scalar and fermionic dark matter models. No evidence for dark matter production has been found. This allows us to set the most sensitive limits on the $A'$ couplings to photons for masses $m_{A'} \lesssim 0.35$ GeV, and to exclude scalar and Majorana dark matter with the $蠂-A'$ coupling $伪_D \leq 0.1$ for masses $0.001 \lesssim m_蠂\lesssim 0.1$ GeV and $3m_蠂\leq m_{A'}$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02404v1-abstract-full').style.display = 'none'; document.getElementById('2307.02404v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 7 figures. arXiv admin note: text overlap with arXiv:1906.00176</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2023-130 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.19411">arXiv:2305.19411</a> <span> [<a href="https://arxiv.org/pdf/2305.19411">pdf</a>, <a href="https://arxiv.org/format/2305.19411">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> </div> </div> <p class="title is-5 mathjax"> Measurement of the intrinsic hadronic contamination in the NA64$-e$ high-purity $e^+/e^-$ beam at CERN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Oberhauser%2C+B+B">B. Banto Oberhauser</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bisio%2C+P">P. Bisio</a>, <a href="/search/hep-ex?searchtype=author&query=Bondi%2C+M">M. Bondi</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=H%22osgen%2C+M">M. H"osgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Kambar%2C+Y">Y. Kambar</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a> , et al. (43 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.19411v2-abstract-short" style="display: inline;"> In this study, we present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c momentum. The analysis was performed using data collected by the NA64-$e$ experiment in 2022. Our study is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64-E… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.19411v2-abstract-full').style.display = 'inline'; document.getElementById('2305.19411v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.19411v2-abstract-full" style="display: none;"> In this study, we present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c momentum. The analysis was performed using data collected by the NA64-$e$ experiment in 2022. Our study is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64-ECAL and NA64-HCAL detectors. We determined the intrinsic hadronic contamination by comparing the results obtained using the nominal electron/positron beamline configuration with those obtained in a dedicated setup, in which only hadrons impinged on the detector. The significant differences in the experimental signatures of electrons and hadrons motivated our approach, resulting in a small and well-controlled systematic uncertainty for the measurement. Our study allowed us to precisely determine the intrinsic hadronic contamination, which represents a crucial parameter for the NA64 experiment in which the hadron contaminants may result in non-trivial backgrounds. Moreover, we performed dedicated Monte Carlo simulations for the hadron production induced by the primary T2 target. We found a good agreement between measurements and simulation results, confirming the validity of the applied methodology and our evaluation of the intrinsic hadronic contamination. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.19411v2-abstract-full').style.display = 'none'; document.getElementById('2305.19411v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2023-108 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.09979">arXiv:2207.09979</a> <span> [<a href="https://arxiv.org/pdf/2207.09979">pdf</a>, <a href="https://arxiv.org/format/2207.09979">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.129.161801">10.1103/PhysRevLett.129.161801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for a New B-L Z' Gauge Boson with the NA64 Experiment at CERN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Banto-Oberhauser%2C+B">B. Banto-Oberhauser</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bisio%2C+P">P. Bisio</a>, <a href="/search/hep-ex?searchtype=author&query=Bondi%2C+M">M. Bondi</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V">V. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a> , et al. (33 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.09979v2-abstract-short" style="display: inline;"> A search for a new $Z'$ gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22e11 electrons on target collected during 2016-2021 runs no signal events were found. This allows to derive new constraints on the $Z'-e$ coupling stre… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.09979v2-abstract-full').style.display = 'inline'; document.getElementById('2207.09979v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.09979v2-abstract-full" style="display: none;"> A search for a new $Z'$ gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22e11 electrons on target collected during 2016-2021 runs no signal events were found. This allows to derive new constraints on the $Z'-e$ coupling strength, which for the mass range $0.3 < m_{Z'} < 100$ MeV are more stringent compared to those obtained from the neutrino-electron scattering data. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.09979v2-abstract-full').style.display = 'none'; document.getElementById('2207.09979v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures. Revised shorter version, Fig.3 updated, published in Physical Review Letters</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2022-156 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys.Rev.Lett. 129, 161801 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.06040">arXiv:2206.06040</a> <span> [<a href="https://arxiv.org/pdf/2206.06040">pdf</a>, <a href="https://arxiv.org/format/2206.06040">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> </div> <p class="title is-5 mathjax"> The AWAKE Run 2 programme and beyond </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Gschwendtner%2C+E">Edda Gschwendtner</a>, <a href="/search/hep-ex?searchtype=author&query=Lotov%2C+K">Konstantin Lotov</a>, <a href="/search/hep-ex?searchtype=author&query=Muggli%2C+P">Patric Muggli</a>, <a href="/search/hep-ex?searchtype=author&query=Wing%2C+M">Matthew Wing</a>, <a href="/search/hep-ex?searchtype=author&query=Agnello%2C+R">Riccardo Agnello</a>, <a href="/search/hep-ex?searchtype=author&query=Ahdida%2C+C+C">Claudia Christina Ahdida</a>, <a href="/search/hep-ex?searchtype=author&query=Goncalves%2C+M+C+A">Maria Carolina Amoedo Goncalves</a>, <a href="/search/hep-ex?searchtype=author&query=Andrebe%2C+Y">Yanis Andrebe</a>, <a href="/search/hep-ex?searchtype=author&query=Apsimon%2C+O">Oznur Apsimon</a>, <a href="/search/hep-ex?searchtype=author&query=Apsimon%2C+R">Robert Apsimon</a>, <a href="/search/hep-ex?searchtype=author&query=Arnesano%2C+J+M">Jordan Matias Arnesano</a>, <a href="/search/hep-ex?searchtype=author&query=Bachmann%2C+A">Anna-Maria Bachmann</a>, <a href="/search/hep-ex?searchtype=author&query=Barrientos%2C+D">Diego Barrientos</a>, <a href="/search/hep-ex?searchtype=author&query=Batsch%2C+F">Fabian Batsch</a>, <a href="/search/hep-ex?searchtype=author&query=Bencini%2C+V">Vittorio Bencini</a>, <a href="/search/hep-ex?searchtype=author&query=Bergamaschi%2C+M">Michele Bergamaschi</a>, <a href="/search/hep-ex?searchtype=author&query=Blanchard%2C+P">Patrick Blanchard</a>, <a href="/search/hep-ex?searchtype=author&query=Burrows%2C+P+N">Philip Nicholas Burrows</a>, <a href="/search/hep-ex?searchtype=author&query=Buttensch%C3%B6n%2C+B">Birger Buttensch枚n</a>, <a href="/search/hep-ex?searchtype=author&query=Caldwell%2C+A">Allen Caldwell</a>, <a href="/search/hep-ex?searchtype=author&query=Chappell%2C+J">James Chappell</a>, <a href="/search/hep-ex?searchtype=author&query=Chevallay%2C+E">Eric Chevallay</a>, <a href="/search/hep-ex?searchtype=author&query=Chung%2C+M">Moses Chung</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D+A">David Andrew Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Damerau%2C+H">Heiko Damerau</a> , et al. (77 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.06040v1-abstract-short" style="display: inline;"> Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. Use of high energy protons to drive wakefields in plasma has been demonstrated during Run 1 of the AWAKE programme at CERN. Protons of energy 400 GeV drove wakefields that accelerated electrons to 2 GeV in under 10 m of plasma. The AWAKE collaboration is now embarking on Run 2 with the main aims to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.06040v1-abstract-full').style.display = 'inline'; document.getElementById('2206.06040v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.06040v1-abstract-full" style="display: none;"> Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. Use of high energy protons to drive wakefields in plasma has been demonstrated during Run 1 of the AWAKE programme at CERN. Protons of energy 400 GeV drove wakefields that accelerated electrons to 2 GeV in under 10 m of plasma. The AWAKE collaboration is now embarking on Run 2 with the main aims to demonstrate stable accelerating gradients of 0.5-1 GV/m, preserve emittance of the electron bunches during acceleration and develop plasma sources scalable to 100s of metres and beyond. By the end of Run 2, the AWAKE scheme should be able to provide electron beams for particle physics experiments and several possible experiments have already been evaluated. This article summarises the programme of AWAKE Run 2 and how it will be achieved as well as the possible application of the AWAKE scheme to novel particle physics experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.06040v1-abstract-full').style.display = 'none'; document.getElementById('2206.06040v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 8 figures. Submitted to Symmetry journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.03101">arXiv:2206.03101</a> <span> [<a href="https://arxiv.org/pdf/2206.03101">pdf</a>, <a href="https://arxiv.org/format/2206.03101">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevD.106.032015">10.1103/PhysRevD.106.032015 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for a light muon-philic $Z^\prime$ with the NA64-$e$ experiment at CERN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Oberhauser%2C+B+B">B. Banto Oberhauser</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bisio%2C+P">P. Bisio</a>, <a href="/search/hep-ex?searchtype=author&query=Bond%C3%AC%2C+M">M. Bond矛</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=H%C3%B6sgen%2C+M">M. H枚sgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a> , et al. (36 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.03101v3-abstract-short" style="display: inline;"> The extension of Standard Model made by inclusion of additional $U(1)$ gauge $L_渭-L_蟿$ symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in $B$ meson decays. This model predicts the existence of a new, light $Z^\prime$ vector boson, predominantly coupled to second and third generation leptons, whose interaction with e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.03101v3-abstract-full').style.display = 'inline'; document.getElementById('2206.03101v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.03101v3-abstract-full" style="display: none;"> The extension of Standard Model made by inclusion of additional $U(1)$ gauge $L_渭-L_蟿$ symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in $B$ meson decays. This model predicts the existence of a new, light $Z^\prime$ vector boson, predominantly coupled to second and third generation leptons, whose interaction with electrons is due to a loop mechanism involving muons and taus. In this work, we present a rigorous evaluation of the upper limits in the $Z^\prime$ parameter space, obtained from the analysis of the data collected by the NA64-$e$ experiment at CERN SPS, that performed a search for light dark matter with $2.84\times10^{11}$ electrons impinging with 100 GeV on an active thick target. The resulting limits, despite being included in a region already investigated by neutrino experiments,touch the muon $g-2$ preferred band for values of the $Z^\prime$ mass of order of 1 MeV. The sensitivity projections for the future high-statistics NA64-$e$ runs demonstrate the power of the electrons/positron beam approach in this theoretical scenario. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.03101v3-abstract-full').style.display = 'none'; document.getElementById('2206.03101v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 9 figures. This version was accepted for publication</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.12893">arXiv:2109.12893</a> <span> [<a href="https://arxiv.org/pdf/2109.12893">pdf</a>, <a href="https://arxiv.org/format/2109.12893">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1748-0221/16/11/P11031">10.1088/1748-0221/16/11/P11031 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Analysis of Proton Bunch Parameters in the AWAKE Experiment </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Hafych%2C+V">V. Hafych</a>, <a href="/search/hep-ex?searchtype=author&query=Caldwell%2C+A">A. Caldwell</a>, <a href="/search/hep-ex?searchtype=author&query=Agnello%2C+R">R. Agnello</a>, <a href="/search/hep-ex?searchtype=author&query=Ahdida%2C+C+C">C. C. Ahdida</a>, <a href="/search/hep-ex?searchtype=author&query=Aladi%2C+M">M. Aladi</a>, <a href="/search/hep-ex?searchtype=author&query=Goncalves%2C+M+C+A">M. C. Amoedo Goncalves</a>, <a href="/search/hep-ex?searchtype=author&query=Andrebe%2C+Y">Y. Andrebe</a>, <a href="/search/hep-ex?searchtype=author&query=Apsimon%2C+O">O. Apsimon</a>, <a href="/search/hep-ex?searchtype=author&query=Apsimon%2C+R">R. Apsimon</a>, <a href="/search/hep-ex?searchtype=author&query=Bachmann%2C+A+-">A. -M. Bachmann</a>, <a href="/search/hep-ex?searchtype=author&query=Baistrukov%2C+M+A">M. A. Baistrukov</a>, <a href="/search/hep-ex?searchtype=author&query=Batsch%2C+F">F. Batsch</a>, <a href="/search/hep-ex?searchtype=author&query=Bergamaschi%2C+M">M. Bergamaschi</a>, <a href="/search/hep-ex?searchtype=author&query=Blanchard%2C+P">P. Blanchard</a>, <a href="/search/hep-ex?searchtype=author&query=Burrows%2C+P+N">P. N. Burrows</a>, <a href="/search/hep-ex?searchtype=author&query=Buttensch%C3%B6n%2C+B">B. Buttensch枚n</a>, <a href="/search/hep-ex?searchtype=author&query=Chappell%2C+J">J. Chappell</a>, <a href="/search/hep-ex?searchtype=author&query=Chevallay%2C+E">E. Chevallay</a>, <a href="/search/hep-ex?searchtype=author&query=Chung%2C+M">M. Chung</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D+A">D. A. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Damerau%2C+H">H. Damerau</a>, <a href="/search/hep-ex?searchtype=author&query=Davut%2C+C">C. Davut</a>, <a href="/search/hep-ex?searchtype=author&query=Demeter%2C+G">G. Demeter</a>, <a href="/search/hep-ex?searchtype=author&query=Dexter%2C+A">A. Dexter</a>, <a href="/search/hep-ex?searchtype=author&query=Doebert%2C+S">S. Doebert</a> , et al. (63 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.12893v1-abstract-short" style="display: inline;"> A precise characterization of the incoming proton bunch parameters is required to accurately simulate the self-modulation process in the Advanced Wakefield Experiment (AWAKE). This paper presents an analysis of the parameters of the incoming proton bunches used in the later stages of the AWAKE Run 1 data-taking period. The transverse structure of the bunch is observed at multiple positions along t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.12893v1-abstract-full').style.display = 'inline'; document.getElementById('2109.12893v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.12893v1-abstract-full" style="display: none;"> A precise characterization of the incoming proton bunch parameters is required to accurately simulate the self-modulation process in the Advanced Wakefield Experiment (AWAKE). This paper presents an analysis of the parameters of the incoming proton bunches used in the later stages of the AWAKE Run 1 data-taking period. The transverse structure of the bunch is observed at multiple positions along the beamline using scintillating or optical transition radiation screens. The parameters of a model that describes the bunch transverse dimensions and divergence are fitted to represent the observed data using Bayesian inference. The analysis is tested on simulated data and then applied to the experimental data. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.12893v1-abstract-full').style.display = 'none'; document.getElementById('2109.12893v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.04195">arXiv:2108.04195</a> <span> [<a href="https://arxiv.org/pdf/2108.04195">pdf</a>, <a href="https://arxiv.org/format/2108.04195">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevD.104.L091701">10.1103/PhysRevD.104.L091701 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Improved exclusion limit for light dark matter from $e^+e^-$ annihilation in NA64 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y">Yu. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Bondi%2C+M">M. Bondi</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V">V. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Celentano%2C+A">A. Celentano</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A">A. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A">A. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S">S. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R">R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V">V. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S">S. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S">S. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hoesgen%2C+M">M. Hoesgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V">V. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A">A. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a> , et al. (33 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.04195v2-abstract-short" style="display: inline;"> The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson $A^\prime$ were set by the NA64 experiment for the mass region $m_{A^\prime}\lesssim 250$ MeV, by analyzing data from the interaction of $2.84\cdot10^{11}$ 100-GeV electrons with an active thick target and searching for missing-energy events. In this work, by includ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.04195v2-abstract-full').style.display = 'inline'; document.getElementById('2108.04195v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.04195v2-abstract-full" style="display: none;"> The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson $A^\prime$ were set by the NA64 experiment for the mass region $m_{A^\prime}\lesssim 250$ MeV, by analyzing data from the interaction of $2.84\cdot10^{11}$ 100-GeV electrons with an active thick target and searching for missing-energy events. In this work, by including $A^\prime$ production via secondary positron annihilation with atomic electrons, we extend these limits in the $200$-$300$ MeV region by almost an order of magnitude, touching for the first time the dark matter relic density constrained parameter combinations. Our new results demonstrate the power of the resonant annihilation process in missing energy dark-matter searches, paving the road to future dedicated $e^+$ beam efforts. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.04195v2-abstract-full').style.display = 'none'; document.getElementById('2108.04195v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Version accepted for publication as a Letter in Phys. Rev. D</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2021-164 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.02021">arXiv:2107.02021</a> <span> [<a href="https://arxiv.org/pdf/2107.02021">pdf</a>, <a href="https://arxiv.org/format/2107.02021">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1140/epjc/s10052-021-09705-5">10.1140/epjc/s10052-021-09705-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Cazzaniga%2C+C">C. Cazzaniga</a>, <a href="/search/hep-ex?searchtype=author&query=Odagiu%2C+P">P. Odagiu</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Bueno%2C+L+M">L. Molina Bueno</a>, <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Girod%2C+S">S. Girod</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=H%C3%B6sgen%2C+M">M. H枚sgen</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a> , et al. (33 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.02021v2-abstract-short" style="display: inline;"> We report the results of a search for a new vector boson ($A'$) decaying into two dark matter particles $蠂_1 蠂_2$ of different mass. The heavier $蠂_2$ particle subsequently decays to $蠂_1$ and $A' \to e^- e^+$. For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remark… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.02021v2-abstract-full').style.display = 'inline'; document.getElementById('2107.02021v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.02021v2-abstract-full" style="display: none;"> We report the results of a search for a new vector boson ($A'$) decaying into two dark matter particles $蠂_1 蠂_2$ of different mass. The heavier $蠂_2$ particle subsequently decays to $蠂_1$ and $A' \to e^- e^+$. For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay $A'\to 蠂\overline蠂$ and axion-like or pseudo-scalar particles $a \to 纬纬$. With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for $A'$ masses from 2$m_e$ up to 390 MeV and mixing parameter $蔚$ between $3\times10^{-5}$ and $2\times10^{-2}$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.02021v2-abstract-full').style.display = 'none'; document.getElementById('2107.02021v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.13342">arXiv:2104.13342</a> <span> [<a href="https://arxiv.org/pdf/2104.13342">pdf</a>, <a href="https://arxiv.org/format/2104.13342">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevD.104.L111102">10.1103/PhysRevD.104.L111102 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for pseudoscalar bosons decaying into $e^+e^-$ pairs in the NA64 experiment at the CERN SPS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hoesgen%2C+M">M. Hoesgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a> , et al. (30 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.13342v3-abstract-short" style="display: inline;"> We report the results of a search for a light pseudoscalar particle $a$ that couples to electrons and decays to $e^+e^-$ performed using the high-energy CERN SPS H4 electron beam. If such pseudoscalar with a mass $\simeq 17$ MeV exists, it could explain the ATOMKI anomaly. We used the NA64 data samples collected in the "visible mode" configuration with total statistics corresponding to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.13342v3-abstract-full').style.display = 'inline'; document.getElementById('2104.13342v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.13342v3-abstract-full" style="display: none;"> We report the results of a search for a light pseudoscalar particle $a$ that couples to electrons and decays to $e^+e^-$ performed using the high-energy CERN SPS H4 electron beam. If such pseudoscalar with a mass $\simeq 17$ MeV exists, it could explain the ATOMKI anomaly. We used the NA64 data samples collected in the "visible mode" configuration with total statistics corresponding to $8.4\times 10^{10}$ electrons on target (EOT) in 2017 and 2018. In order to increase sensitivity to small coupling parameter $蔚$ we used also the data collected in 2016-2018 in the "invisible mode" configuration of NA64 with a total statistics corresponding to $2.84\times 10^{11}$ EOT. A thorough analysis of both these data samples in the sense of background and efficiency estimations was already performed and reported in our previous papers devoted to the search for light vector particles and axion-like particles (ALP). In this work we recalculate the signal yields, which are different due to different cross section and life time of a pseudoscalar particle $a$, and perform a new statistical analysis. As a result, the region of the two dimensional parameter space $m_a - 蔚$ in the mass range from 1 to 17.1 MeV is excluded. At the mass of the ATOMKI anomaly the values of $蔚$ in the range $2.1 \times 10^{-4} < 蔚< 3.2 \times 10^{-4}$ are excluded. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.13342v3-abstract-full').style.display = 'none'; document.getElementById('2104.13342v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 2 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.01885">arXiv:2102.01885</a> <span> [<a href="https://arxiv.org/pdf/2102.01885">pdf</a>, <a href="https://arxiv.org/format/2102.01885">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.126.211802">10.1103/PhysRevLett.126.211802 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraints on New Physics in the Electron g-2 from a Search for Invisible Decays of a Scalar, Pseudoscalar, Vector, and Axial Vector </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a> , et al. (27 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.01885v1-abstract-short" style="display: inline;"> We performed a search for a new generic $X$ boson, which could be a scalar ($S$), pseudoscalar ($P$), vector ($V$) or an axial vector ($A$) particle produced in the 100 GeV electron scattering off nuclei, $e^- Z \to e^- Z X$, followed by its invisible decay in the NA64 experiment at CERN. No evidence for such process was found in the full NA64 data set of $2.84\times 10^{11}$ electrons on target.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.01885v1-abstract-full').style.display = 'inline'; document.getElementById('2102.01885v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.01885v1-abstract-full" style="display: none;"> We performed a search for a new generic $X$ boson, which could be a scalar ($S$), pseudoscalar ($P$), vector ($V$) or an axial vector ($A$) particle produced in the 100 GeV electron scattering off nuclei, $e^- Z \to e^- Z X$, followed by its invisible decay in the NA64 experiment at CERN. No evidence for such process was found in the full NA64 data set of $2.84\times 10^{11}$ electrons on target. We place new bounds on the $S, P, V, A$ coupling strengths to electrons, and set constraints on their contributions to the electron anomalous magnetic moment $a_e$, $|螖a_{X}| \lesssim 10^{-15} - 10^{-13}$ for the $X$ mass region $m_X\lesssim 1$ GeV. These results are an order of magnitude more sensitive compared to the current accuracy on $a_e$ from the electron $g-2$ experiments and recent high-precision determination of the fine structure constant. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.01885v1-abstract-full').style.display = 'none'; document.getElementById('2102.01885v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2021-017 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 126, 211802 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.02756">arXiv:2009.02756</a> <span> [<a href="https://arxiv.org/pdf/2009.02756">pdf</a>, <a href="https://arxiv.org/format/2009.02756">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> </div> <p class="title is-5 mathjax"> Hunting down the X17 boson at the CERN SPS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Andreev%2C+Y+M">Yu. M. Andreev</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V">V. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+.">A . Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A">A. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S">S. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R">R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V">V. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S">S. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Girod%2C+S">S. Girod</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S">S. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V">V. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A">A. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D">D. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M">M. Kirsanov</a> , et al. (31 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.02756v2-abstract-short" style="display: inline;"> Recently, the ATOMKI experiment has reported new evidence for the excess of $e^+ e^-$ events with a mass $\sim$17 MeV in the nuclear transitions of $^4$He, that they previously observed in measurements with $^8$Be. These observations could be explained by the existence of a new vector $X17$ boson. So far, the search for the decay $X17 \rightarrow e^+ e^-$ with the NA64 experiment at the CERN SPS g… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.02756v2-abstract-full').style.display = 'inline'; document.getElementById('2009.02756v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.02756v2-abstract-full" style="display: none;"> Recently, the ATOMKI experiment has reported new evidence for the excess of $e^+ e^-$ events with a mass $\sim$17 MeV in the nuclear transitions of $^4$He, that they previously observed in measurements with $^8$Be. These observations could be explained by the existence of a new vector $X17$ boson. So far, the search for the decay $X17 \rightarrow e^+ e^-$ with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining $X17$ parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the $X17$ decay with the proposed method. To reach this goal an optimization of the $X17$ production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results [Phys. Rev. D101, 071101 (2020)], validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate shows that the goal of the proposed search is feasible. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.02756v2-abstract-full').style.display = 'none'; document.getElementById('2009.02756v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.16160">arXiv:2006.16160</a> <span> [<a href="https://arxiv.org/pdf/2006.16160">pdf</a>, <a href="https://arxiv.org/format/2006.16160">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2020.164902">10.1016/j.nima.2020.164902 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement and application of electron stripping of ultrarelativistic $^{208}\textrm{Pb}^{81+}$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D+A">D. A. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Bauche%2C+J">J. Bauche</a>, <a href="/search/hep-ex?searchtype=author&query=Cascella%2C+M">M. Cascella</a>, <a href="/search/hep-ex?searchtype=author&query=Chappell%2C+J">J. Chappell</a>, <a href="/search/hep-ex?searchtype=author&query=Fernandez%2C+R+A">R. A. Fernandez</a>, <a href="/search/hep-ex?searchtype=author&query=Gorgisyan%2C+I">I. Gorgisyan</a>, <a href="/search/hep-ex?searchtype=author&query=Gschwendtner%2C+E">E. Gschwendtner</a>, <a href="/search/hep-ex?searchtype=author&query=Jolly%2C+S">S. Jolly</a>, <a href="/search/hep-ex?searchtype=author&query=Kain%2C+V">V. Kain</a>, <a href="/search/hep-ex?searchtype=author&query=Keeble%2C+F">F. Keeble</a>, <a href="/search/hep-ex?searchtype=author&query=Krasny%2C+M+W">M. W. Krasny</a>, <a href="/search/hep-ex?searchtype=author&query=La+Penna%2C+P">P. La Penna</a>, <a href="/search/hep-ex?searchtype=author&query=Mazzoni%2C+S">S. Mazzoni</a>, <a href="/search/hep-ex?searchtype=author&query=Petrenko%2C+A">A. Petrenko</a>, <a href="/search/hep-ex?searchtype=author&query=Quattri%2C+M">M. Quattri</a>, <a href="/search/hep-ex?searchtype=author&query=Wing%2C+M">M. Wing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.16160v1-abstract-short" style="display: inline;"> New measurements of the stripping cross-section for ultrarelativistic hydrogen-like lead ions passing through aluminium and silicon have been performed at the Advanced Wakefield experiment at CERN. Agreement with existing measurements and theory has been obtained. Improvements in terms of electron beam quality and ion beam diagnostic capability, as well as further applications of such an electron… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.16160v1-abstract-full').style.display = 'inline'; document.getElementById('2006.16160v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.16160v1-abstract-full" style="display: none;"> New measurements of the stripping cross-section for ultrarelativistic hydrogen-like lead ions passing through aluminium and silicon have been performed at the Advanced Wakefield experiment at CERN. Agreement with existing measurements and theory has been obtained. Improvements in terms of electron beam quality and ion beam diagnostic capability, as well as further applications of such an electron beam, are discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.16160v1-abstract-full').style.display = 'none'; document.getElementById('2006.16160v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.02710">arXiv:2005.02710</a> <span> [<a href="https://arxiv.org/pdf/2005.02710">pdf</a>, <a href="https://arxiv.org/format/2005.02710">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.125.081801">10.1103/PhysRevLett.125.081801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for Axionlike and Scalar Particles with the NA64 Experiment </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a> , et al. (30 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2005.02710v3-abstract-short" style="display: inline;"> We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.02710v3-abstract-full').style.display = 'inline'; document.getElementById('2005.02710v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.02710v3-abstract-full" style="display: none;"> We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCAL module, serving as shielding, and would be observed either through their $a(s)\to纬纬$ decay in the rest of the HCAL detector or as events with large missing energy if the a(s) decays downstream of the HCAL. This method allows for the probing the a(s) parameter space, including those from generic axion models, inaccessible to previous experiments. No evidence of such processes has been found from the analysis of the data corresponding to $2.84\times10^{11}$ electrons on target allowing to set new limits on the $a(s)纬纬$-coupling strength for a(s) masses below 55 MeV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.02710v3-abstract-full').style.display = 'none'; document.getElementById('2005.02710v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This publication is dedicated to the memory of our colleague Danila Tlisov. 7 pages, 5 figures, revised version accepted for publication in Phys. Rev. Lett</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2020-068 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 125, 081801 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.11389">arXiv:1912.11389</a> <span> [<a href="https://arxiv.org/pdf/1912.11389">pdf</a>, <a href="https://arxiv.org/format/1912.11389">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevD.101.071101">10.1103/PhysRevD.101.071101 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Improved limits on a hypothetical X(16.7) boson and a dark photon decaying into $e^+e^-$ pairs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Bernhard%2C+J">J. Bernhard</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hoesgen%2C+M">M. Hoesgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a> , et al. (29 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.11389v2-abstract-short" style="display: inline;"> The improved results on a direct search for a new X(16.7 MeV) boson which could explain the anomalous excess of $e^+e^-$ pairs observed in the excited 8Be nucleus decays ("Berillium anomaly") are reported. Due to its coupling to electrons, the X boson could be produced in the bremsstrahlung reaction e-Z -> e-ZX by a high-energy beam of electrons incident on active target in the NA64 experiment at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.11389v2-abstract-full').style.display = 'inline'; document.getElementById('1912.11389v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.11389v2-abstract-full" style="display: none;"> The improved results on a direct search for a new X(16.7 MeV) boson which could explain the anomalous excess of $e^+e^-$ pairs observed in the excited 8Be nucleus decays ("Berillium anomaly") are reported. Due to its coupling to electrons, the X boson could be produced in the bremsstrahlung reaction e-Z -> e-ZX by a high-energy beam of electrons incident on active target in the NA64 experiment at the CERN SPS and observed through its subsequent decay into $e^+e^-$ pair. No evidence for such decays was found from the combined analysis of the data samples with total statistics corresponding to 8.4\times 10^{10} electrons on target collected in 2017 and 2018. This allows to set the new limits on the $X$--$e^-$ coupling in the range 1.2 \times 10^{-4} < 蔚_e < 6.8 \times 10^{-4}, excluding part of the parameter space favored by the Berillium anomaly. We also set new bounds on the mixing strength of photons with dark photons (A') from non-observation of the decay $A' \to e^+e^-$ of the bremsstrahlung A' with a mass below 24 MeV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.11389v2-abstract-full').style.display = 'none'; document.getElementById('1912.11389v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 5 figures, 1 table. arXiv admin note: substantial text overlap with arXiv:1803.07748</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2019-284 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. D 101, 071101 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1906.00176">arXiv:1906.00176</a> <span> [<a href="https://arxiv.org/pdf/1906.00176">pdf</a>, <a href="https://arxiv.org/format/1906.00176">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.123.121801">10.1103/PhysRevLett.123.121801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dark matter search in missing energy events with NA64 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a>, <a href="/search/hep-ex?searchtype=author&query=Konorov%2C+I+V">I. V. Konorov</a>, <a href="/search/hep-ex?searchtype=author&query=Kovalenko%2C+S+G">S. G. Kovalenko</a> , et al. (26 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1906.00176v3-abstract-short" style="display: inline;"> A search for sub-GeV dark matter production mediated by a new vector boson $A'$, called dark photon, is performed by the NA64 experiment in missing energy events from 100 GeV electron interactions in an active beam dump at the CERN SPS. From the analysis of the data collected in the years 2016, 2017, and 2018 with $2.84\times10^{11}$ electrons on target no evidence of such a process has been found… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1906.00176v3-abstract-full').style.display = 'inline'; document.getElementById('1906.00176v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1906.00176v3-abstract-full" style="display: none;"> A search for sub-GeV dark matter production mediated by a new vector boson $A'$, called dark photon, is performed by the NA64 experiment in missing energy events from 100 GeV electron interactions in an active beam dump at the CERN SPS. From the analysis of the data collected in the years 2016, 2017, and 2018 with $2.84\times10^{11}$ electrons on target no evidence of such a process has been found. The most stringent constraints on the $A'$ mixing strength with photons and the parameter space for the scalar and fermionic dark matter in the mass range $\lesssim 0.2$ GeV are derived, thus demonstrating the power of the active beam dump approach for the dark matter search. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1906.00176v3-abstract-full').style.display = 'none'; document.getElementById('1906.00176v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 June, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures, version accepted for publication in Phys. Rev. Lett. arXiv admin note: text overlap with arXiv:1710.00971, arXiv:1610.02988</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2019-116 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 123, 121801 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.02460">arXiv:1905.02460</a> <span> [<a href="https://arxiv.org/pdf/1905.02460">pdf</a>, <a href="https://arxiv.org/format/1905.02460">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.5109315">10.1063/1.5109315 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multiple hit reconstruction in large area multiplexed detectors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Radics%2C+B">B. Radics</a>, <a href="/search/hep-ex?searchtype=author&query=Janka%2C+G">G. Janka</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D+A">D. A. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Procureur%2C+S">S. Procureur</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1905.02460v1-abstract-short" style="display: inline;"> A novel approach is presented to unfold particle hit positions in tracking detectors with multiplexed readout representing an underdetermined system of linear equations. The method does not use any prior information about the hit positions, the only assumption in the procedure is that isolated hit signals generated on consecutive detector strips follow a smooth distribution. Ambiguities introduced… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.02460v1-abstract-full').style.display = 'inline'; document.getElementById('1905.02460v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.02460v1-abstract-full" style="display: none;"> A novel approach is presented to unfold particle hit positions in tracking detectors with multiplexed readout representing an underdetermined system of linear equations. The method does not use any prior information about the hit positions, the only assumption in the procedure is that isolated hit signals generated on consecutive detector strips follow a smooth distribution. Ambiguities introduced by charge sharing from multiplexing are reduced by using a regularization technique. We have tested this method on a multiplexed 50x50 cm$^{2}$ Micromegas detector with 1037 strips and only 61 readout channels, using cosmic rays, and we have found that single and multiple clusters of hits can be reconstructed with high efficiency. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.02460v1-abstract-full').style.display = 'none'; document.getElementById('1905.02460v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Review of Scientific Instruments 90, 093305 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.05752">arXiv:1902.05752</a> <span> [<a href="https://arxiv.org/pdf/1902.05752">pdf</a>, <a href="https://arxiv.org/format/1902.05752">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2019.05.067">10.1016/j.nima.2019.05.067 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A magnetic spectrometer to measure electron bunches accelerated at AWAKE </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Bauche%2C+J">J. Bauche</a>, <a href="/search/hep-ex?searchtype=author&query=Biskup%2C+B">B. Biskup</a>, <a href="/search/hep-ex?searchtype=author&query=Cascella%2C+M">M. Cascella</a>, <a href="/search/hep-ex?searchtype=author&query=Chappell%2C+J">J. Chappell</a>, <a href="/search/hep-ex?searchtype=author&query=Chritin%2C+N">N. Chritin</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Deacon%2C+L">L. Deacon</a>, <a href="/search/hep-ex?searchtype=author&query=Deliege%2C+Q">Q. Deliege</a>, <a href="/search/hep-ex?searchtype=author&query=Gorgisyan%2C+I">I. Gorgisyan</a>, <a href="/search/hep-ex?searchtype=author&query=Hansen%2C+J">J. Hansen</a>, <a href="/search/hep-ex?searchtype=author&query=Jolly%2C+S">S. Jolly</a>, <a href="/search/hep-ex?searchtype=author&query=Keeble%2C+F">F. Keeble</a>, <a href="/search/hep-ex?searchtype=author&query=La+Penna%2C+P">P. La Penna</a>, <a href="/search/hep-ex?searchtype=author&query=Mazzoni%2C+S">S. Mazzoni</a>, <a href="/search/hep-ex?searchtype=author&query=Godoy%2C+D+M">D. Medina Godoy</a>, <a href="/search/hep-ex?searchtype=author&query=Petrenko%2C+A">A. Petrenko</a>, <a href="/search/hep-ex?searchtype=author&query=Quattri%2C+M">M. Quattri</a>, <a href="/search/hep-ex?searchtype=author&query=Schneider%2C+T">T. Schneider</a>, <a href="/search/hep-ex?searchtype=author&query=Sherwood%2C+P">P. Sherwood</a>, <a href="/search/hep-ex?searchtype=author&query=Vorozhtsov%2C+A">A. Vorozhtsov</a>, <a href="/search/hep-ex?searchtype=author&query=Wing%2C+M">M. Wing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1902.05752v1-abstract-short" style="display: inline;"> A magnetic spectrometer has been developed for the AWAKE experiment at CERN in order to measure the energy distribution of bunches of electrons accelerated in wakefields generated by proton bunches in plasma. AWAKE is a proof-of-principle experiment for proton-driven plasma wakefield acceleration, using proton bunches from the SPS. Electron bunches are accelerated to $\mathcal{O}$(1 GeV) in a rubi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.05752v1-abstract-full').style.display = 'inline'; document.getElementById('1902.05752v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.05752v1-abstract-full" style="display: none;"> A magnetic spectrometer has been developed for the AWAKE experiment at CERN in order to measure the energy distribution of bunches of electrons accelerated in wakefields generated by proton bunches in plasma. AWAKE is a proof-of-principle experiment for proton-driven plasma wakefield acceleration, using proton bunches from the SPS. Electron bunches are accelerated to $\mathcal{O}$(1 GeV) in a rubidium plasma cell and then separated from the proton bunches via a dipole magnet. The dipole magnet also induces an energy-dependent spatial horizontal spread on the electron bunch which then impacts on a scintillator screen. The scintillation photons emitted are transported via three highly-reflective mirrors to an intensified CCD camera, housed in a dark room, which passes the images to the CERN controls system for storage and further analysis. Given the known magnetic field and determination of the efficiencies of the system, the spatial spread of the scintillation photons can be converted to an electron energy distribution. A lamp attached on a rail in front of the scintillator is used to calibrate the optical system, with calibration of the scintillator screen's response to electrons carried out at the CLEAR facility at CERN. In this article, the design of the AWAKE spectrometer is presented, along with the calibrations carried out and expected performance such that the energy distribution of accelerated electrons can be measured. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.05752v1-abstract-full').style.display = 'none'; document.getElementById('1902.05752v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1808.09759">arXiv:1808.09759</a> <span> [<a href="https://arxiv.org/pdf/1808.09759">pdf</a>, <a href="https://arxiv.org/format/1808.09759">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Plasma Physics">physics.plasm-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-018-0485-4">10.1038/s41586-018-0485-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Acceleration of electrons in the plasma wakefield of a proton bunch </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=The+AWAKE+Collaboration"> The AWAKE Collaboration</a>, <a href="/search/hep-ex?searchtype=author&query=Adli%2C+E">E. Adli</a>, <a href="/search/hep-ex?searchtype=author&query=Ahuja%2C+A">A. Ahuja</a>, <a href="/search/hep-ex?searchtype=author&query=Apsimon%2C+O">O. Apsimon</a>, <a href="/search/hep-ex?searchtype=author&query=Apsimon%2C+R">R. Apsimon</a>, <a href="/search/hep-ex?searchtype=author&query=Bachmann%2C+A+-">A. -M. Bachmann</a>, <a href="/search/hep-ex?searchtype=author&query=Barrientos%2C+D">D. Barrientos</a>, <a href="/search/hep-ex?searchtype=author&query=Batsch%2C+F">F. Batsch</a>, <a href="/search/hep-ex?searchtype=author&query=Bauche%2C+J">J. Bauche</a>, <a href="/search/hep-ex?searchtype=author&query=Olsen%2C+V+K+B">V. K. Berglyd Olsen</a>, <a href="/search/hep-ex?searchtype=author&query=Bernardini%2C+M">M. Bernardini</a>, <a href="/search/hep-ex?searchtype=author&query=Bohl%2C+T">T. Bohl</a>, <a href="/search/hep-ex?searchtype=author&query=Bracco%2C+C">C. Bracco</a>, <a href="/search/hep-ex?searchtype=author&query=Braunmueller%2C+F">F. Braunmueller</a>, <a href="/search/hep-ex?searchtype=author&query=Burt%2C+G">G. Burt</a>, <a href="/search/hep-ex?searchtype=author&query=Buttenschoen%2C+B">B. Buttenschoen</a>, <a href="/search/hep-ex?searchtype=author&query=Caldwell%2C+A">A. Caldwell</a>, <a href="/search/hep-ex?searchtype=author&query=Cascella%2C+M">M. Cascella</a>, <a href="/search/hep-ex?searchtype=author&query=Chappell%2C+J">J. Chappell</a>, <a href="/search/hep-ex?searchtype=author&query=Chevallay%2C+E">E. Chevallay</a>, <a href="/search/hep-ex?searchtype=author&query=Chung%2C+M">M. Chung</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Damerau%2C+H">H. Damerau</a>, <a href="/search/hep-ex?searchtype=author&query=Deacon%2C+L">L. Deacon</a>, <a href="/search/hep-ex?searchtype=author&query=Deubner%2C+L+H">L. H. Deubner</a> , et al. (69 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1808.09759v2-abstract-short" style="display: inline;"> High energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. In order to increase the energy or reduce the size of the accelerator, new acceleration schemes need to be developed. Plasma wakefield acceleration, in which the electrons in a plasma are excited, leading to strong electric fields, is one s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.09759v2-abstract-full').style.display = 'inline'; document.getElementById('1808.09759v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1808.09759v2-abstract-full" style="display: none;"> High energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. In order to increase the energy or reduce the size of the accelerator, new acceleration schemes need to be developed. Plasma wakefield acceleration, in which the electrons in a plasma are excited, leading to strong electric fields, is one such promising novel acceleration technique. Pioneering experiments have shown that an intense laser pulse or electron bunch traversing a plasma, drives electric fields of 10s GV/m and above. These values are well beyond those achieved in conventional RF accelerators which are limited to ~0.1 GV/m. A limitation of laser pulses and electron bunches is their low stored energy, which motivates the use of multiple stages to reach very high energies. The use of proton bunches is compelling, as they have the potential to drive wakefields and accelerate electrons to high energy in a single accelerating stage. The long proton bunches currently available can be used, as they undergo self-modulation, a particle-plasma interaction which longitudinally splits the bunch into a series of high density microbunches, which then act resonantly to create large wakefields. The AWAKE experiment at CERN uses intense bunches of protons, each of energy 400 GeV, with a total bunch energy of 19 kJ, to drive a wakefield in a 10 m long plasma. Bunches of electrons are injected into the wakefield formed by the proton microbunches. This paper presents measurements of electrons accelerated up to 2 GeV at AWAKE. This constitutes the first demonstration of proton-driven plasma wakefield acceleration. The potential for this scheme to produce very high energy electron bunches in a single accelerating stage means that the results shown here are a significant step towards the development of future high energy particle accelerators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.09759v2-abstract-full').style.display = 'none'; document.getElementById('1808.09759v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 August, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 4 figures. Updated acknowledgements and one reference</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1803.07748">arXiv:1803.07748</a> <span> [<a href="https://arxiv.org/pdf/1803.07748">pdf</a>, <a href="https://arxiv.org/format/1803.07748">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.120.231802">10.1103/PhysRevLett.120.231802 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for a Hypothetical 16.7 MeV Gauge Boson and Dark Photons in the NA64 Experiment at CERN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Enik%2C+T">T. Enik</a>, <a href="/search/hep-ex?searchtype=author&query=Charitonidis%2C+N">N. Charitonidis</a>, <a href="/search/hep-ex?searchtype=author&query=Feshchenko%2C+A">A. Feshchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Jeckel%2C+M">M. Jeckel</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Kekelidze%2C+G">G. Kekelidze</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a>, <a href="/search/hep-ex?searchtype=author&query=Konorov%2C+I+V">I. V. Konorov</a>, <a href="/search/hep-ex?searchtype=author&query=Kovalenko%2C+S+G">S. G. Kovalenko</a> , et al. (23 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1803.07748v2-abstract-short" style="display: inline;"> We report the first results on a direct search for a new 16.7 MeV boson (X) which could explain the anomalous excess of e+e- pairs observed in the excited Be-8 nucleus decays. Due to its coupling to electrons, the X could be produced in the bremsstrahlung reaction e- Z -> e- Z X by a 100 GeV e- beam incident on an active target in the NA64 experiment at the CERN SPS and observed through the subseq… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.07748v2-abstract-full').style.display = 'inline'; document.getElementById('1803.07748v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1803.07748v2-abstract-full" style="display: none;"> We report the first results on a direct search for a new 16.7 MeV boson (X) which could explain the anomalous excess of e+e- pairs observed in the excited Be-8 nucleus decays. Due to its coupling to electrons, the X could be produced in the bremsstrahlung reaction e- Z -> e- Z X by a 100 GeV e- beam incident on an active target in the NA64 experiment at the CERN SPS and observed through the subsequent decay into an e+e- pair. With 5.4\times 10^{10} electrons on target, no evidence for such decays was found, allowing to set first limits on the X-e^- coupling in the range 1.3\times 10^{-4} < 蔚_e < 4.2\times 10^{-4} excluding part of the allowed parameter space. We also set new bounds on the mixing strength of photons with dark photons (A') from non-observation of the decay A'->e+e- of the bremsstrahlung A' with a mass <~ 23 MeV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.07748v2-abstract-full').style.display = 'none'; document.getElementById('1803.07748v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures. Title changed as suggested by Journal; references added; version published in Phys. Rev. Lett</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> CERN-EP-2018-043 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 120, 231802 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.00971">arXiv:1710.00971</a> <span> [<a href="https://arxiv.org/pdf/1710.00971">pdf</a>, <a href="https://arxiv.org/format/1710.00971">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevD.97.072002">10.1103/PhysRevD.97.072002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for vector mediator of Dark Matter production in invisible decay mode </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=NA64+Collaboration"> NA64 Collaboration</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V+E">V. E. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A+G">A. G. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dubinin%2C+F">F. Dubinin</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Emmenegger%2C+S">S. Emmenegger</a>, <a href="/search/hep-ex?searchtype=author&query=Fabich%2C+A">A. Fabich</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gerassimov%2C+S+G">S. G. Gerassimov</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a>, <a href="/search/hep-ex?searchtype=author&query=Konorov%2C+I+V">I. V. Konorov</a>, <a href="/search/hep-ex?searchtype=author&query=Kovalenko%2C+S+G">S. G. Kovalenko</a>, <a href="/search/hep-ex?searchtype=author&query=Kramarenko%2C+V+A">V. A. Kramarenko</a> , et al. (19 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1710.00971v2-abstract-short" style="display: inline;"> A search is performed for a new sub-GeV vector boson ($A'$) mediated production of Dark Matter ($蠂$) in the fixed-target experiment, NA64, at the CERN SPS. The $A'$, called dark photon, could be generated in the reaction $ e^- Z \to e^- Z A'$ of 100 GeV electrons dumped against an active target which is followed by the prompt invisible decay $A' \to 蠂\overline蠂$. The experimental signature of this… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.00971v2-abstract-full').style.display = 'inline'; document.getElementById('1710.00971v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.00971v2-abstract-full" style="display: none;"> A search is performed for a new sub-GeV vector boson ($A'$) mediated production of Dark Matter ($蠂$) in the fixed-target experiment, NA64, at the CERN SPS. The $A'$, called dark photon, could be generated in the reaction $ e^- Z \to e^- Z A'$ of 100 GeV electrons dumped against an active target which is followed by the prompt invisible decay $A' \to 蠂\overline蠂$. The experimental signature of this process would be an event with an isolated electron and large missing energy in the detector. From the analysis of the data sample collected in 2016 corresponding to $4.3\times10^{10}$ electrons on target no evidence of such a process has been found. New stringent constraints on the $A'$ mixing strength with photons, $10^{-5}\lesssim 蔚\lesssim 10^{-2}$, for the $A'$ mass range $m_{A'} \lesssim 1$ GeV are derived. For models considering scalar and fermionic thermal Dark Matter interacting with the visible sector through the vector portal the 90% C.L. limits $10^{-11}\lesssim y \lesssim 10^{-6}$ on the dark-matter parameter $y = 蔚^2 伪_D (\frac{m_蠂}{m_{A'}})^4 $ are obtained for the dark coupling constant $伪_D = 0.5$ and dark-matter masses $0.001 \lesssim m_蠂\lesssim 0.5 $ GeV. The lower limits $伪_D \gtrsim 10^{-3} $ for pseudo-Dirac Dark Matter in the mass region $m_蠂\lesssim 0.05 $ GeV are more stringent than the corresponding bounds from beam dump experiments. The results are obtained by using tree level, exact calculations of the $A'$ production cross-sections, which turn out to be significantly smaller compared to the one obtained in the Weizs盲cker-Williams approximation for the mass region $m_{A'} \gtrsim 0.1$ GeV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.00971v2-abstract-full').style.display = 'none'; document.getElementById('1710.00971v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 17 figures, version accepted for publication in PRD</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. D 97, 072002 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1708.04087">arXiv:1708.04087</a> <span> [<a href="https://arxiv.org/pdf/1708.04087">pdf</a>, <a href="https://arxiv.org/format/1708.04087">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2017.10.067">10.1016/j.nima.2017.10.067 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Performance of Multiplexed XY Resistive Micromegas detectors in a high intensity beam </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V">V. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A">A. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dubinin%2C+F">F. Dubinin</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Emmenegger%2C+S">S. Emmenegger</a>, <a href="/search/hep-ex?searchtype=author&query=Fabich%2C+A">A. Fabich</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=H%C3%B6sgen%2C+M">M. H枚sgen</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a>, <a href="/search/hep-ex?searchtype=author&query=Konorov%2C+I+V">I. V. Konorov</a>, <a href="/search/hep-ex?searchtype=author&query=Kramarenko%2C+V+A">V. A. Kramarenko</a>, <a href="/search/hep-ex?searchtype=author&query=Kuleshov%2C+S+V">S. V. Kuleshov</a>, <a href="/search/hep-ex?searchtype=author&query=Levchenko%2C+E">E. Levchenko</a>, <a href="/search/hep-ex?searchtype=author&query=Lyubovitskij%2C+V+E">V. E. Lyubovitskij</a>, <a href="/search/hep-ex?searchtype=author&query=Lysan%2C+V">V. Lysan</a>, <a href="/search/hep-ex?searchtype=author&query=Mamon%2C+S">S. Mamon</a> , et al. (16 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1708.04087v1-abstract-short" style="display: inline;"> We present the performance of multiplexed XY resistive Micromegas detectors tested in the CERN SPS 100 GeV/c electron beam at intensities up to 3.3 $\times$ 10$^5$ e$^- $/(s$\cdot$cm$^2$). So far, all studies with multiplexed Micromegas have only been reported for tests with radioactive sources and cosmic rays. The use of multiplexed modules in high intensity environments was not explored due to t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1708.04087v1-abstract-full').style.display = 'inline'; document.getElementById('1708.04087v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1708.04087v1-abstract-full" style="display: none;"> We present the performance of multiplexed XY resistive Micromegas detectors tested in the CERN SPS 100 GeV/c electron beam at intensities up to 3.3 $\times$ 10$^5$ e$^- $/(s$\cdot$cm$^2$). So far, all studies with multiplexed Micromegas have only been reported for tests with radioactive sources and cosmic rays. The use of multiplexed modules in high intensity environments was not explored due to the effect of ambiguities in the reconstruction of the hit point caused by the multiplexing feature. At the beam intensities analysed in this work and with a multiplexing factor of 5, more than 50% level of ambiguity is introduced. Our results prove that by using the additional information of cluster size and integrated charge from the signal clusters induced on the XY strips, the ambiguities can be reduced to a level below 2%. The tested detectors are used in the CERN NA64 experiment for tracking the incoming particles bending in a magnetic field in order to reconstruct their momentum. The average hit detection efficiency of each module was found to be $\sim$ 96% at the highest beam intensities. By using four modules a tracking resolution of 1.1% was obtained with $\sim$ 85% combined tracking efficiency. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1708.04087v1-abstract-full').style.display = 'none'; document.getElementById('1708.04087v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 August, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2017. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1707.04591">arXiv:1707.04591</a> <span> [<a href="https://arxiv.org/pdf/1707.04591">pdf</a>, <a href="https://arxiv.org/format/1707.04591">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> </div> <p class="title is-5 mathjax"> US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Battaglieri%2C+M">Marco Battaglieri</a>, <a href="/search/hep-ex?searchtype=author&query=Belloni%2C+A">Alberto Belloni</a>, <a href="/search/hep-ex?searchtype=author&query=Chou%2C+A">Aaron Chou</a>, <a href="/search/hep-ex?searchtype=author&query=Cushman%2C+P">Priscilla Cushman</a>, <a href="/search/hep-ex?searchtype=author&query=Echenard%2C+B">Bertrand Echenard</a>, <a href="/search/hep-ex?searchtype=author&query=Essig%2C+R">Rouven Essig</a>, <a href="/search/hep-ex?searchtype=author&query=Estrada%2C+J">Juan Estrada</a>, <a href="/search/hep-ex?searchtype=author&query=Feng%2C+J+L">Jonathan L. Feng</a>, <a href="/search/hep-ex?searchtype=author&query=Flaugher%2C+B">Brenna Flaugher</a>, <a href="/search/hep-ex?searchtype=author&query=Fox%2C+P+J">Patrick J. Fox</a>, <a href="/search/hep-ex?searchtype=author&query=Graham%2C+P">Peter Graham</a>, <a href="/search/hep-ex?searchtype=author&query=Hall%2C+C">Carter Hall</a>, <a href="/search/hep-ex?searchtype=author&query=Harnik%2C+R">Roni Harnik</a>, <a href="/search/hep-ex?searchtype=author&query=Hewett%2C+J">JoAnne Hewett</a>, <a href="/search/hep-ex?searchtype=author&query=Incandela%2C+J">Joseph Incandela</a>, <a href="/search/hep-ex?searchtype=author&query=Izaguirre%2C+E">Eder Izaguirre</a>, <a href="/search/hep-ex?searchtype=author&query=McKinsey%2C+D">Daniel McKinsey</a>, <a href="/search/hep-ex?searchtype=author&query=Pyle%2C+M">Matthew Pyle</a>, <a href="/search/hep-ex?searchtype=author&query=Roe%2C+N">Natalie Roe</a>, <a href="/search/hep-ex?searchtype=author&query=Rybka%2C+G">Gray Rybka</a>, <a href="/search/hep-ex?searchtype=author&query=Sikivie%2C+P">Pierre Sikivie</a>, <a href="/search/hep-ex?searchtype=author&query=Tait%2C+T+M+P">Tim M. P. Tait</a>, <a href="/search/hep-ex?searchtype=author&query=Toro%2C+N">Natalia Toro</a>, <a href="/search/hep-ex?searchtype=author&query=Van+De+Water%2C+R">Richard Van De Water</a>, <a href="/search/hep-ex?searchtype=author&query=Weiner%2C+N">Neal Weiner</a> , et al. (226 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1707.04591v1-abstract-short" style="display: inline;"> This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017. </span> <span class="abstract-full has-text-grey-dark mathjax" id="1707.04591v1-abstract-full" style="display: none;"> This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.04591v1-abstract-full').style.display = 'none'; document.getElementById('1707.04591v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 July, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">102 pages + references</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.06198">arXiv:1703.06198</a> <span> [<a href="https://arxiv.org/pdf/1703.06198">pdf</a>, <a href="https://arxiv.org/format/1703.06198">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> </div> <p class="title is-5 mathjax"> High efficiency cyclotron trap assisted positron moderator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Gerchow%2C+L">L. Gerchow</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D+A">D. A. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Braccini%2C+S">S. Braccini</a>, <a href="/search/hep-ex?searchtype=author&query=D%C3%B6beli%2C+M">M. D枚beli</a>, <a href="/search/hep-ex?searchtype=author&query=Kirch%2C+K">K. Kirch</a>, <a href="/search/hep-ex?searchtype=author&query=K%C3%B6ster%2C+U">U. K枚ster</a>, <a href="/search/hep-ex?searchtype=author&query=M%C3%BCller%2C+A">A. M眉ller</a>, <a href="/search/hep-ex?searchtype=author&query=Van+Der+Meulen%2C+N+P">N. P. Van Der Meulen</a>, <a href="/search/hep-ex?searchtype=author&query=Vermeulen%2C+C">C. Vermeulen</a>, <a href="/search/hep-ex?searchtype=author&query=Rubbia%2C+A">A. Rubbia</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1703.06198v1-abstract-short" style="display: inline;"> We report the realisation of a cyclotron trap assisted positron tungsten moderator for the conversion of positrons with a broad keV- few MeV energy spectrum to a mono-energetic eV beam with an efficiency of 1.8(2)% defined as the ratio of the slow positrons divided by the $尾^+$ activity of the radioactive source. This is an improvement of almost two orders of magnitude compared to the state of the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.06198v1-abstract-full').style.display = 'inline'; document.getElementById('1703.06198v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.06198v1-abstract-full" style="display: none;"> We report the realisation of a cyclotron trap assisted positron tungsten moderator for the conversion of positrons with a broad keV- few MeV energy spectrum to a mono-energetic eV beam with an efficiency of 1.8(2)% defined as the ratio of the slow positrons divided by the $尾^+$ activity of the radioactive source. This is an improvement of almost two orders of magnitude compared to the state of the art of tungsten moderators. The simulation validated with this measurement suggests that using an optimised setup even higher efficiencies are achievable. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.06198v1-abstract-full').style.display = 'none'; document.getElementById('1703.06198v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 Figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.05993">arXiv:1703.05993</a> <span> [<a href="https://arxiv.org/pdf/1703.05993">pdf</a>, <a href="https://arxiv.org/format/1703.05993">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.nima.2017.05.028">10.1016/j.nima.2017.05.028 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High purity 100 GeV electron identification with synchrotron radiation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V">V. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Chumakov%2C+A">A. Chumakov</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dubinin%2C+F">F. Dubinin</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Emmenegger%2C+S">S. Emmenegger</a>, <a href="/search/hep-ex?searchtype=author&query=Fabich%2C+A">A. Fabich</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=H%C3%B6sgen%2C+M">M. H枚sgen</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a>, <a href="/search/hep-ex?searchtype=author&query=Konorov%2C+I+V">I. V. Konorov</a>, <a href="/search/hep-ex?searchtype=author&query=Kramarenko%2C+V+A">V. A. Kramarenko</a>, <a href="/search/hep-ex?searchtype=author&query=Kuleshov%2C+S+V">S. V. Kuleshov</a>, <a href="/search/hep-ex?searchtype=author&query=Lyubovitskij%2C+V+E">V. E. Lyubovitskij</a>, <a href="/search/hep-ex?searchtype=author&query=Lysan%2C+V">V. Lysan</a>, <a href="/search/hep-ex?searchtype=author&query=Matveev%2C+V+A">V. A. Matveev</a>, <a href="/search/hep-ex?searchtype=author&query=Mikhailov%2C+Y+V">Yu. V. Mikhailov</a> , et al. (14 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1703.05993v1-abstract-short" style="display: inline;"> In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.05993v1-abstract-full').style.display = 'inline'; document.getElementById('1703.05993v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.05993v1-abstract-full" style="display: none;"> In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet. A 100 GeV $蟺^-$ beam is used to test the method in the NA64 experiment resulting in a suppression factor of $10^{-5}$ while the efficiency for electron detection is $\sim$95%. The spectra and the rejection factors are in very good agreement with the Monte Carlo simulation. The reported suppression factors are significantly better than previously achieved. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.05993v1-abstract-full').style.display = 'none'; document.getElementById('1703.05993v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1612.07814">arXiv:1612.07814</a> <span> [<a href="https://arxiv.org/pdf/1612.07814">pdf</a>, <a href="https://arxiv.org/format/1612.07814">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Enhanced anti-hydrogen ion production </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D+A">D. A. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Husson%2C+A">A. Husson</a>, <a href="/search/hep-ex?searchtype=author&query=Lunney%2C+D">D. Lunney</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1612.07814v2-abstract-short" style="display: inline;"> The production of anti-hydrogen ions in the GBAR experiment will occur via a two step charge exchange process. In a first reaction, the anti-protons from the ELENA ring at CERN will capture a positron from a positronium target producing anti-hydrogen atoms. Those interacting in the same positronium target will produce in a second step anti-hydrogen ions. This results in a dependence for the anti-i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.07814v2-abstract-full').style.display = 'inline'; document.getElementById('1612.07814v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1612.07814v2-abstract-full" style="display: none;"> The production of anti-hydrogen ions in the GBAR experiment will occur via a two step charge exchange process. In a first reaction, the anti-protons from the ELENA ring at CERN will capture a positron from a positronium target producing anti-hydrogen atoms. Those interacting in the same positronium target will produce in a second step anti-hydrogen ions. This results in a dependence for the anti-ions production rate which is roughly proportional to the positronium density squared. We present a scheme to increase the anti-ions production rate in the GBAR experiment by tailoring the anti-proton to the positron pulse in order to maximise the temporal overlap of Ps and anti-protons. Detailed simulations show that an order of magnitude could be gained by bunching the anti-protons from ELENA. In order to avoid losses in their capture in the Paul trap due to the energy spread introduced by the bunching, debunching with a symmetrical inverted pulse can be applied to the anti-hydrogen ions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.07814v2-abstract-full').style.display = 'none'; document.getElementById('1612.07814v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 January, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 6 figures, prepared for the proceedings of the WAG2015 conference</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.02988">arXiv:1610.02988</a> <span> [<a href="https://arxiv.org/pdf/1610.02988">pdf</a>, <a href="https://arxiv.org/format/1610.02988">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.118.011802">10.1103/PhysRevLett.118.011802 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Search for invisible decays of sub-GeV dark photons in missing-energy events at the CERN SPS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=NA64+Collaboration"> NA64 Collaboration</a>, <a href="/search/hep-ex?searchtype=author&query=Banerjee%2C+D">D. Banerjee</a>, <a href="/search/hep-ex?searchtype=author&query=Burtsev%2C+V">V. Burtsev</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Depero%2C+E">E. Depero</a>, <a href="/search/hep-ex?searchtype=author&query=Dermenev%2C+A+V">A. V. Dermenev</a>, <a href="/search/hep-ex?searchtype=author&query=Donskov%2C+S+V">S. V. Donskov</a>, <a href="/search/hep-ex?searchtype=author&query=Dubinin%2C+F">F. Dubinin</a>, <a href="/search/hep-ex?searchtype=author&query=Dusaev%2C+R+R">R. R. Dusaev</a>, <a href="/search/hep-ex?searchtype=author&query=Emmenegger%2C+S">S. Emmenegger</a>, <a href="/search/hep-ex?searchtype=author&query=Fabich%2C+A">A. Fabich</a>, <a href="/search/hep-ex?searchtype=author&query=Frolov%2C+V+N">V. N. Frolov</a>, <a href="/search/hep-ex?searchtype=author&query=Gardikiotis%2C+A">A. Gardikiotis</a>, <a href="/search/hep-ex?searchtype=author&query=Gninenko%2C+S+N">S. N. Gninenko</a>, <a href="/search/hep-ex?searchtype=author&query=Hosgen%2C+M">M. Hosgen</a>, <a href="/search/hep-ex?searchtype=author&query=Kachanov%2C+V+A">V. A. Kachanov</a>, <a href="/search/hep-ex?searchtype=author&query=Karneyeu%2C+A+E">A. E. Karneyeu</a>, <a href="/search/hep-ex?searchtype=author&query=Ketzer%2C+B">B. Ketzer</a>, <a href="/search/hep-ex?searchtype=author&query=Kirpichnikov%2C+D+V">D. V. Kirpichnikov</a>, <a href="/search/hep-ex?searchtype=author&query=Kirsanov%2C+M+M">M. M. Kirsanov</a>, <a href="/search/hep-ex?searchtype=author&query=Kovalenko%2C+S+G">S. G. Kovalenko</a>, <a href="/search/hep-ex?searchtype=author&query=Kramarenko%2C+V+A">V. A. Kramarenko</a>, <a href="/search/hep-ex?searchtype=author&query=Kravchuk%2C+L+V">L. V. Kravchuk</a>, <a href="/search/hep-ex?searchtype=author&query=Krasnikov%2C+N+V">N. V. Krasnikov</a> , et al. (22 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1610.02988v2-abstract-short" style="display: inline;"> We report on a direct search for sub-GeV dark photons (A') which might be produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The A's would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75\cdot 10^… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.02988v2-abstract-full').style.display = 'inline'; document.getElementById('1610.02988v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.02988v2-abstract-full" style="display: none;"> We report on a direct search for sub-GeV dark photons (A') which might be produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The A's would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75\cdot 10^{9} electrons on target. We set new limits on the 纬-A' mixing strength and exclude the invisible A' with a mass < 100 MeV as an explanation of the muon g_渭-2 anomaly. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.02988v2-abstract-full').style.display = 'none'; document.getElementById('1610.02988v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures; Typos corrected, references added</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 118, 011802 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.08632">arXiv:1608.08632</a> <span> [<a href="https://arxiv.org/pdf/1608.08632">pdf</a>, <a href="https://arxiv.org/format/1608.08632">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Nuclear Experiment">nucl-ex</span> </div> </div> <p class="title is-5 mathjax"> Dark Sectors 2016 Workshop: Community Report </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Alexander%2C+J">Jim Alexander</a>, <a href="/search/hep-ex?searchtype=author&query=Battaglieri%2C+M">Marco Battaglieri</a>, <a href="/search/hep-ex?searchtype=author&query=Echenard%2C+B">Bertrand Echenard</a>, <a href="/search/hep-ex?searchtype=author&query=Essig%2C+R">Rouven Essig</a>, <a href="/search/hep-ex?searchtype=author&query=Graham%2C+M">Matthew Graham</a>, <a href="/search/hep-ex?searchtype=author&query=Izaguirre%2C+E">Eder Izaguirre</a>, <a href="/search/hep-ex?searchtype=author&query=Jaros%2C+J">John Jaros</a>, <a href="/search/hep-ex?searchtype=author&query=Krnjaic%2C+G">Gordan Krnjaic</a>, <a href="/search/hep-ex?searchtype=author&query=Mardon%2C+J">Jeremy Mardon</a>, <a href="/search/hep-ex?searchtype=author&query=Morrissey%2C+D">David Morrissey</a>, <a href="/search/hep-ex?searchtype=author&query=Nelson%2C+T">Tim Nelson</a>, <a href="/search/hep-ex?searchtype=author&query=Perelstein%2C+M">Maxim Perelstein</a>, <a href="/search/hep-ex?searchtype=author&query=Pyle%2C+M">Matt Pyle</a>, <a href="/search/hep-ex?searchtype=author&query=Ritz%2C+A">Adam Ritz</a>, <a href="/search/hep-ex?searchtype=author&query=Schuster%2C+P">Philip Schuster</a>, <a href="/search/hep-ex?searchtype=author&query=Shuve%2C+B">Brian Shuve</a>, <a href="/search/hep-ex?searchtype=author&query=Toro%2C+N">Natalia Toro</a>, <a href="/search/hep-ex?searchtype=author&query=Van+De+Water%2C+R+G">Richard G Van De Water</a>, <a href="/search/hep-ex?searchtype=author&query=Akerib%2C+D">Daniel Akerib</a>, <a href="/search/hep-ex?searchtype=author&query=An%2C+H">Haipeng An</a>, <a href="/search/hep-ex?searchtype=author&query=Aniol%2C+K">Konrad Aniol</a>, <a href="/search/hep-ex?searchtype=author&query=Arnquist%2C+I+J">Isaac J. Arnquist</a>, <a href="/search/hep-ex?searchtype=author&query=Asner%2C+D+M">David M. Asner</a>, <a href="/search/hep-ex?searchtype=author&query=Back%2C+H+O">Henning O. Back</a>, <a href="/search/hep-ex?searchtype=author&query=Baker%2C+K">Keith Baker</a> , et al. (179 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1608.08632v1-abstract-short" style="display: inline;"> This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years. </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.08632v1-abstract-full" style="display: none;"> This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.08632v1-abstract-full').style.display = 'none'; document.getElementById('1608.08632v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">66 pages, 15 figures, 3 tables. Workshop website and agenda: http://www-conf.slac.stanford.edu/darksectors2016/ https://indico.cern.ch/event/507783/ Editors: J. Alexander, M. Battaglieri, B. Echenard, R. Essig, M. Graham, E. Izaguirre, J. Jaros, G. Krnjaic, J. Mardon, D. Morrissey, T. Nelson, M. Perelstein, M. Pyle, A. Ritz, P. Schuster, B. Shuve, N. Toro, R. Van De Water</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1606.05977">arXiv:1606.05977</a> <span> [<a href="https://arxiv.org/pdf/1606.05977">pdf</a>, <a href="https://arxiv.org/format/1606.05977">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevD.94.052008">10.1103/PhysRevD.94.052008 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The anti-proton charge radius </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D">D. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Heiss%2C+M+W">M. W. Heiss</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1606.05977v4-abstract-short" style="display: inline;"> The upcoming operation of the Extra Low ENergy Antiprotons (ELENA) ring at CERN, the upgrade of the anti-proton decelerator (AD), and the installation in the AD hall of an intense slow positron beam with an expected flux of $10^{8}$ e$^+$/s will open the possibility for new experiments with anti-hydrogen ($\bar{\text{H}}$). Here we propose a scheme to measure the Lamb shift of $\bar{\text{H}}$. Fo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.05977v4-abstract-full').style.display = 'inline'; document.getElementById('1606.05977v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1606.05977v4-abstract-full" style="display: none;"> The upcoming operation of the Extra Low ENergy Antiprotons (ELENA) ring at CERN, the upgrade of the anti-proton decelerator (AD), and the installation in the AD hall of an intense slow positron beam with an expected flux of $10^{8}$ e$^+$/s will open the possibility for new experiments with anti-hydrogen ($\bar{\text{H}}$). Here we propose a scheme to measure the Lamb shift of $\bar{\text{H}}$. For a month of data taking, we anticipate an uncertainty of 100 ppm. This will provide a test of CPT and the first determination of the anti-proton charge radius at the level of 10%. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.05977v4-abstract-full').style.display = 'none'; document.getElementById('1606.05977v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 July, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 June, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 Figures, v4 refs 19 added</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. D 94, 052008 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1503.05755">arXiv:1503.05755</a> <span> [<a href="https://arxiv.org/pdf/1503.05755">pdf</a>, <a href="https://arxiv.org/ps/1503.05755">ps</a>, <a href="https://arxiv.org/format/1503.05755">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s10751-015-1158-4">10.1007/s10751-015-1158-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of positronium annihilation in the 2S state: towards a new measurement of the 1S-2S transition frequency </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/hep-ex?searchtype=author&query=Cooke%2C+D+A">D. A. Cooke</a>, <a href="/search/hep-ex?searchtype=author&query=Crivelli%2C+P">P. Crivelli</a>, <a href="/search/hep-ex?searchtype=author&query=Alnis%2C+J">J. Alnis</a>, <a href="/search/hep-ex?searchtype=author&query=Antognini%2C+A">A. Antognini</a>, <a href="/search/hep-ex?searchtype=author&query=Brown%2C+B">B. Brown</a>, <a href="/search/hep-ex?searchtype=author&query=Friedreich%2C+S">S. Friedreich</a>, <a href="/search/hep-ex?searchtype=author&query=Gabard%2C+A">A. Gabard</a>, <a href="/search/hep-ex?searchtype=author&query=Haensch%2C+T+W">T. W. Haensch</a>, <a href="/search/hep-ex?searchtype=author&query=Kirch%2C+K">K. Kirch</a>, <a href="/search/hep-ex?searchtype=author&query=Rubbia%2C+A">A. Rubbia</a>, <a href="/search/hep-ex?searchtype=author&query=Vrankovic%2C+V">V. Vrankovic</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1503.05755v1-abstract-short" style="display: inline;"> We report the first observation of the annihilation of positronium from the 2S state. Positronium (Ps) is excited with a two-photon transition from the 1S to the 2S state where its lifetime is increased by a factor of eight compared to the ground state due to the decrease in the overlap of the positron electron wavefunction. The yield of delayed annihilation photons detected as a function of laser… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.05755v1-abstract-full').style.display = 'inline'; document.getElementById('1503.05755v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1503.05755v1-abstract-full" style="display: none;"> We report the first observation of the annihilation of positronium from the 2S state. Positronium (Ps) is excited with a two-photon transition from the 1S to the 2S state where its lifetime is increased by a factor of eight compared to the ground state due to the decrease in the overlap of the positron electron wavefunction. The yield of delayed annihilation photons detected as a function of laser frequency is used as a new method of detecting laser-excited Ps in the 2S state. This can be considered the first step towards a new high precision measurement of the 1S-2S Ps line. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.05755v1-abstract-full').style.display = 'none'; document.getElementById('1503.05755v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 March, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 Figures, proceedings EXA 2014, accepted for publication in Hyperfine Interactions</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 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