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<button class="button is-small 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/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/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/2206.03101">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/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/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/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/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> </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 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/about">About</a></li> <li><a href="https://info.arxiv.org/help">Help</a></li> </ul> </div> <div class="column"> <ul class="nav-spaced"> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>contact arXiv</title><desc>Click here to contact arXiv</desc><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg> <a href="https://info.arxiv.org/help/contact.html"> Contact</a> </li> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>subscribe to arXiv mailings</title><desc>Click here to subscribe</desc><path d="M476 3.2L12.5 270.6c-18.1 10.4-15.8 35.6 2.2 43.2L121 358.4l287.3-253.2c5.5-4.9 13.3 2.6 8.6 8.3L176 407v80.5c0 23.6 28.5 32.9 42.5 15.8L282 426l124.6 52.2c14.2 6 30.4-2.9 33-18.2l72-432C515 7.8 493.3-6.8 476 3.2z"/></svg> <a href="https://info.arxiv.org/help/subscribe"> Subscribe</a> </li> </ul> </div> </div> </div>   <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/license/index.html">Copyright</a></li> <li><a href="https://info.arxiv.org/help/policies/privacy_policy.html">Privacy Policy</a></li> </ul> </div> <div class="column sorry-app-links"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/web_accessibility.html">Web Accessibility Assistance</a></li> <li> <p class="help"> <a class="a11y-main-link" href="https://status.arxiv.org" target="_blank">arXiv Operational Status <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" class="icon filter-dark_grey" role="presentation"><path d="M224.3 273l-136 136c-9.4 9.4-24.6 9.4-33.9 0l-22.6-22.6c-9.4-9.4-9.4-24.6 0-33.9l96.4-96.4-96.4-96.4c-9.4-9.4-9.4-24.6 0-33.9L54.3 103c9.4-9.4 24.6-9.4 33.9 0l136 136c9.5 9.4 9.5 24.6.1 34z"/></svg></a><br> Get status notifications via <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/email/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg>email</a> or <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/slack/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512" class="icon filter-black" role="presentation"><path d="M94.12 315.1c0 25.9-21.16 47.06-47.06 47.06S0 341 0 315.1c0-25.9 21.16-47.06 47.06-47.06h47.06v47.06zm23.72 0c0-25.9 21.16-47.06 47.06-47.06s47.06 21.16 47.06 47.06v117.84c0 25.9-21.16 47.06-47.06 47.06s-47.06-21.16-47.06-47.06V315.1zm47.06-188.98c-25.9 0-47.06-21.16-47.06-47.06S139 32 164.9 32s47.06 21.16 47.06 47.06v47.06H164.9zm0 23.72c25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06H47.06C21.16 243.96 0 222.8 0 196.9s21.16-47.06 47.06-47.06H164.9zm188.98 47.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06h-47.06V196.9zm-23.72 0c0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06V79.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06V196.9zM283.1 385.88c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06v-47.06h47.06zm0-23.72c-25.9 0-47.06-21.16-47.06-47.06 0-25.9 21.16-47.06 47.06-47.06h117.84c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06H283.1z"/></svg>slack</a> </p> </li> </ul> </div> </div> </div>  </div> </footer> <script src="https://static.arxiv.org/static/base/1.0.0a5/js/member_acknowledgement.js"></script> </body> </html>

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