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<!DOCTYPE html> <html lang="en"> <head> <title>General Relativity and Quantum Cosmology </title> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="apple-touch-icon" sizes="180x180" href="/static/browse/0.3.4/images/icons/apple-touch-icon.png"> <link rel="icon" type="image/png" sizes="32x32" href="/static/browse/0.3.4/images/icons/favicon-32x32.png"> <link rel="icon" type="image/png" sizes="16x16" href="/static/browse/0.3.4/images/icons/favicon-16x16.png"> <link rel="manifest" href="/static/browse/0.3.4/images/icons/site.webmanifest"> <link rel="mask-icon" href="/static/browse/0.3.4/images/icons/safari-pinned-tab.svg" color="#5bbad5"> <meta name="msapplication-TileColor" content="#da532c"> <meta name="theme-color" content="#ffffff"> <link rel="stylesheet" type="text/css" media="screen" href="/static/browse/0.3.4/css/arXiv.css?v=20241206" /> <link rel="stylesheet" type="text/css" media="print" href="/static/browse/0.3.4/css/arXiv-print.css?v=20200611" /> 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2000 entries per page: <a href=/list/gr-qc/new?skip=0&show=1000 rel="nofollow"> fewer</a> | <span style="color: #454545">more</span> | <span style="color: #454545">all</span> </div> <dl id='articles'> <h3>New submissions (showing 12 of 12 entries)</h3> <dt> <a name='item1'>[1]</a> <a href ="/abs/2503.15543" title="Abstract" id="2503.15543"> arXiv:2503.15543 </a> [<a href="/pdf/2503.15543" title="Download PDF" id="pdf-2503.15543" aria-labelledby="pdf-2503.15543">pdf</a>, <a href="https://arxiv.org/html/2503.15543v1" title="View HTML" id="html-2503.15543" aria-labelledby="html-2503.15543" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15543" title="Other formats" id="oth-2503.15543" aria-labelledby="oth-2503.15543">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Energy Extraction from Rotating Black Hole with Quintessential Energy through the Penrose Process </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Abbasi,+K+Q">K. Q. Abbasi</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Carneiro,+F+L">F. L. Carneiro</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Moughal,+M+Z+A">M. Z. A. Moughal</a></div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> We investigate the geometry, dynamics, and collision mechanisms in the ergoregion of KerrNewman-AdS black hole influenced by quintessential energy. Particle splittings within the ergoregion are analyzed, demonstrating their role in energy extraction via the Penrose process. Increased spin elongates the ergosphere, while higher quintessential parameters expand static limits and distort photon regions. Prograde orbits benefit from reduced energy and angular momentum due to frame-dragging, whereas retrograde orbits require higher energy. Quintessential energy weakens the gravitational pull, shifts stable orbit radii, and enhances orbital chaos, as indicated by Lyapunov exponents. The Penrose process demonstrates efficiencies ranging from 5% to 35%, with peak efficiency achieved at high spin, but diminishing with increased charge or quintessential energy due to reduced frame-dragging. We derive the exprssion for irreducible mass and discuss its dependence on cosmological and quintessence parameters, revealing their role in limiting extractable energy. </p> </div> </dd> <dt> <a name='item2'>[2]</a> <a href ="/abs/2503.15606" title="Abstract" id="2503.15606"> arXiv:2503.15606 </a> [<a href="/pdf/2503.15606" title="Download PDF" id="pdf-2503.15606" aria-labelledby="pdf-2503.15606">pdf</a>, <a href="https://arxiv.org/html/2503.15606v1" title="View HTML" id="html-2503.15606" aria-labelledby="html-2503.15606" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15606" title="Other formats" id="oth-2503.15606" aria-labelledby="oth-2503.15606">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Perturbations of spinning black holes in dynamical Chern-Simons gravity: Slow rotation quasinormal modes </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Li,+D">Dongjun Li</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Wagle,+P">Pratik Wagle</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Chen,+Y">Yanbei Chen</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Yunes,+N">Nicol谩s Yunes</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 35 pages, 7 figures, 5 tables </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> Gravitational waves offer new ways to test general relativity (GR) in the strong-field regime, including tests involving the ringdown phase of binary black hole mergers, characterized by oscillating and quickly decaying quasinormal modes (QNMs). Recent advances have extended QNM calculations to several theories beyond GR through the development of the modified Teukolsky formalism, including higher derivative gravity and dynamical Chern-Simons (dCS) gravity. Using the modified Teukolsky formalism, we previously derived radial second-order differential equations governing curvature and scalar field perturbations in dCS gravity at leading order in spin. In this work, we compute the QNM frequency shifts for slowly rotating black holes in dCS gravity from these modified Teukolsky equations, and (1) show that the radial equations for Weyl scalars $\Psi_{0,4}$ can be separated into even- and odd-parity parts, confirming that the scalar field couples only to the odd-parity sector; (2) extend the eigenvalue perturbation method to coupled fields; (3) compute the QNM spectrum, obtaining consistent results across independent calculations using different radiation gauges; (4) calculate the overtones in the QNM spectra for the first time in dCS gravity; (5) show that our findings align with previous metric perturbation studies and mark the first QNM spectrum calculation in a non-minimally coupled scalar-tensor theory via the modified Teukolsky formalism. This work lays the foundation for studying fast-rotating black holes in dCS gravity, advancing black hole spectroscopy in beyond-GR contexts. </p> </div> </dd> <dt> <a name='item3'>[3]</a> <a href ="/abs/2503.15773" title="Abstract" id="2503.15773"> arXiv:2503.15773 </a> [<a href="/pdf/2503.15773" title="Download PDF" id="pdf-2503.15773" aria-labelledby="pdf-2503.15773">pdf</a>, <a href="https://arxiv.org/html/2503.15773v1" title="View HTML" id="html-2503.15773" aria-labelledby="html-2503.15773" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15773" title="Other formats" id="oth-2503.15773" aria-labelledby="oth-2503.15773">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Search for continuous gravitational waves from neutron stars in five globular clusters with a phase-tracking hidden Markov model in the third LIGO observing run </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Dunn,+L">L. Dunn</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Melatos,+A">A. Melatos</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Clearwater,+P">P. Clearwater</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Suvorova,+S">S. Suvorova</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Sun,+L">L. Sun</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Moran,+W">W. Moran</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Evans,+R+J">R. J. Evans</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> Accepted for publication in Physical Review D </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; High Energy Astrophysical Phenomena (astro-ph.HE) </div> <p class='mathjax'> A search is performed for continuous gravitational waves emitted by unknown neutron stars in five nearby globular clusters using data from the third Laser Interferometer Gravitational-Wave Observatory (LIGO) observing run, over the frequency range $100$--$800\,\mathrm{Hz}$. The search uses a hidden Markov model to track both the frequency and phase of the continuous wave signal from one coherent segment to the next. It represents the first time that a phase-tracking hidden Markov model has been used in a LIGO search. After applying vetoes to reject candidates consistent with non-Gaussian artifacts, no significant candidates are detected. Estimates of the strain sensitivity at 95\% confidence $h_{0,\mathrm{eff}}^{95\%}$ and corresponding neutron star ellipticity $\epsilon^{95\%}$ are presented. The best strain sensitivity, $h_{0,\mathrm{eff}}^{95\%} = 2.7 \times 10^{-26}$ at $211\,\mathrm{Hz}$, is achieved for the cluster NGC6544. </p> </div> </dd> <dt> <a name='item4'>[4]</a> <a href ="/abs/2503.15776" title="Abstract" id="2503.15776"> arXiv:2503.15776 </a> [<a href="/pdf/2503.15776" title="Download PDF" id="pdf-2503.15776" aria-labelledby="pdf-2503.15776">pdf</a>, <a href="https://arxiv.org/html/2503.15776v1" title="View HTML" id="html-2503.15776" aria-labelledby="html-2503.15776" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15776" title="Other formats" id="oth-2503.15776" aria-labelledby="oth-2503.15776">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Copenhagen Survey on Black Holes and Fundamental Physics </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Chen,+A+Y">Alice Y. Chen</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Halper,+P">Phil Halper</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Afshordi,+N">Niayesh Afshordi</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 18 pages, 12 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th); History and Philosophy of Physics (physics.hist-ph) </div> <p class='mathjax'> The purpose of this survey is to take a snapshot of the attitudes of physicists, which may be useful to sociologists and historians of science. A total of 85 completed surveys were returned out of 151 registered participants of the "Black holes Inside and out" conference, held in Copenhagen in 2024. The survey asked questions about the nature of black holes and some of the most contentious issues in fundamental physics. A number of surprising results were found. For example, some of the leading frameworks, such the cosmological constant, cosmic inflation, or string theory, while most popular, gain less than majority of votes from the participants. The only statement that gains majority approval (by 68% of participants) was that the Big Bang means that "the universe evolved from a hot dense state", not "an absolute beginning time". This provides reasons for caution in describing ideas as consensus in the scientific community when a more nuanced view may be justified. </p> </div> </dd> <dt> <a name='item5'>[5]</a> <a href ="/abs/2503.15992" title="Abstract" id="2503.15992"> arXiv:2503.15992 </a> [<a href="/pdf/2503.15992" title="Download PDF" id="pdf-2503.15992" aria-labelledby="pdf-2503.15992">pdf</a>, <a href="https://arxiv.org/html/2503.15992v1" title="View HTML" id="html-2503.15992" aria-labelledby="html-2503.15992" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15992" title="Other formats" id="oth-2503.15992" aria-labelledby="oth-2503.15992">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Small-scale metric structure and horizons: Probing the nature of gravity </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Pesci,+A">Alessandro Pesci</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 10 pages; to appear in the Journal of Physics: Conference Series (2025), proceedings of DICE2024 </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> A recently developed tool allows for a description of spacetime as a manifold with a Lorentz-invariant (lower) limit length built-in. This is accomplished in terms of geometric quantities depending on two spacetime events (bitensors) and looking at the 2-point function of fields on it, all this being well suited to embody nonlocality at the small scale. What one gets is a metric bitensor with components singular in the coincidence limit of the two events, capable to provide a finite distance in the same limit. We discuss here how this metric structure encompasses also the case of null separated events, and describe some results one obtains with the null qmetric which do have immediate thermodynamic/statistical interpretation for horizons. One of them is that the area transverse to null geodesics converging to a base point goes to a finite value in the coincidence limit (instead of shrinking to 0). We comment on the discreteness this seems to imply for the area of black hole horizons as well as on possible ensuing effects in gravitational waves from binary black hole coalescences. </p> </div> </dd> <dt> <a name='item6'>[6]</a> <a href ="/abs/2503.15995" title="Abstract" id="2503.15995"> arXiv:2503.15995 </a> [<a href="/pdf/2503.15995" title="Download PDF" id="pdf-2503.15995" aria-labelledby="pdf-2503.15995">pdf</a>, <a href="https://arxiv.org/html/2503.15995v1" title="View HTML" id="html-2503.15995" aria-labelledby="html-2503.15995" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15995" title="Other formats" id="oth-2503.15995" aria-labelledby="oth-2503.15995">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> The transition to phenomenological behaviour of static solutions of the Einstein-Dirac system for an increasing number of fermions </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Andr%C3%A9asson,+H">H氓kan Andr茅asson</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Blomquist,+J">Joakim Blomquist</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 29 pages, 14 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> Static spherically symmetric solutions to the Einstein-Dirac system were constructed numerically for the first time in 1999 by Finster, Smoller and Yau \cite{FSY1} in the case of two fermions. In 2020 this result was generalized by Leith, Hooley, Horne and Dritschel \cite{LHHD} to a system consisting of an even number $\kappa$ of fermions. They constructed solutions for $2\leq\kappa\leq 90$. The purpose of the present investigation is to compare the properties of static solutions of the Einstein-Dirac system with static solutions of the Einstein,-Vlasov system as the number of fermions increases, that is, for $2\leq\kappa \leq 180$. Since the Einstein-Vlasov system is a fully classical physical model, whereas the Einstein-Dirac system is semiclassical and thus has a quantum signature, this framework provides an excellent opportunity to study the transition from quantum to classical behaviour. It turns out that even for a comparatively small number of particles, the features of the solutions are remarkably similar. For both systems, we find highly relativistic solutions having a multi-peak structure with strikingly similar characteristics. We also investigate the maximum compactness ratio $\sup 2m/r$ of the solutions. The solutions of both systems share the fundamental properties regarding the maximum compactness ratio and obey the inequality derived in \cite{A2}. Furthermore, we investigate the sign of the pressure components of solutions of the Einstein-Dirac system. For small values of $\kappa$, there are regions where the radial pressure is negative. These regions disappear as $\kappa$ increases. This supports the interpretation we make as a transition from quantum to classical behaviour as the number of fermions increases. </p> </div> </dd> <dt> <a name='item7'>[7]</a> <a href ="/abs/2503.16087" title="Abstract" id="2503.16087"> arXiv:2503.16087 </a> [<a href="/pdf/2503.16087" title="Download PDF" id="pdf-2503.16087" aria-labelledby="pdf-2503.16087">pdf</a>, <a href="https://arxiv.org/html/2503.16087v1" title="View HTML" id="html-2503.16087" aria-labelledby="html-2503.16087" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16087" title="Other formats" id="oth-2503.16087" aria-labelledby="oth-2503.16087">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Long-lived Quasinormal Modes and Gray-Body Factors of black holes and wormholes in dark matter inspired Weyl Gravity </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=L%C3%BCtf%C3%BCo%C4%9Flu,+B+C">B. C. L眉tf眉o臒lu</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 14 Pages, 8 Figures, 8 Tables </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> We calculate quasinormal modes and gray-body factors of a massive scalar field in the background of three compact objects in the Weyl gravity: Schwarzschild-like black holes, known as Mannheim-Kazanas solution, non-Schwrazschild-like black holes and traversable wormholes found recently in [P. Jizba, K. Mudru艌ka, Phys.Rev.D 110 (2024) 12, 124006]. We show that the spectrum of the massive field is qualitatively different from massless one both in the frequency and time domains. While the mass term leads to much longer lifetime of the modes, the arbitrarily long-lived modes, known as quasi-resonances, are not achieved. </p> </div> </dd> <dt> <a name='item8'>[8]</a> <a href ="/abs/2503.16138" title="Abstract" id="2503.16138"> arXiv:2503.16138 </a> [<a href="/pdf/2503.16138" title="Download PDF" id="pdf-2503.16138" aria-labelledby="pdf-2503.16138">pdf</a>, <a href="https://arxiv.org/html/2503.16138v1" title="View HTML" id="html-2503.16138" aria-labelledby="html-2503.16138" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16138" title="Other formats" id="oth-2503.16138" aria-labelledby="oth-2503.16138">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> The entropy of dynamical de Sitter horizons </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Zhao,+J">Jinan Zhao</a></div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; High Energy Physics - Theory (hep-th) </div> <p class='mathjax'> We propose a new formula for the entropy of a dynamical cosmological event horizon, which is valid to leading order for perturbations of a stationary asymptotically de Sitter spacetime. By introducing a nontrivial correction term, we generalize Gibbons and Hawking's first law of event horizons to non-stationary eras. We also develop the non-stationary physical process first law between two arbitrary horizon cross-sections for the cosmological event horizon. </p> </div> </dd> <dt> <a name='item9'>[9]</a> <a href ="/abs/2503.16265" title="Abstract" id="2503.16265"> arXiv:2503.16265 </a> [<a href="/pdf/2503.16265" title="Download PDF" id="pdf-2503.16265" aria-labelledby="pdf-2503.16265">pdf</a>, <a href="https://arxiv.org/html/2503.16265v1" title="View HTML" id="html-2503.16265" aria-labelledby="html-2503.16265" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16265" title="Other formats" id="oth-2503.16265" aria-labelledby="oth-2503.16265">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Spherically symmetric horizonless solutions and their frozen states in Bardeen spacetime with Proca field </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Zhang,+R">Rong Zhang</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Wang,+Y">Yong-Qiang Wang</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 23 pages, 8 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; High Energy Physics - Theory (hep-th) </div> <p class='mathjax'> In this paper, we construct a static spherical symmetric Bardeen-Proca star (BPS) model, which consists of the electromagnetic field and Proca field minimally coupled with gravity. The introduction of the Proca field disrupts the formation of event horizons, ensuring that these solutions are globally regular throughout the spacetime. We obtain families of BPS solutions under several magnetic charge conditions. Based on these results, we further investigate the ADM mass, Noether charge, and energy density distribution of them. We find that when the magnetic charge is sufficiently large, solutions with a critical horizon $r_{cH}$ emerge as $\omega \rightarrow 0$, and the time component of the metric approaches zero inside $r_{cH}$. To an observer at infinity, the collapse process of the matter near the critical horizon appears frozen. Consequently, we refer to the solution with $r_{cH}$ as the frozen Bardeen-Proca star (FBPS). Additionally, we also investigate the circular geodesic orbits of BPS. For the light ring, we find that the light rings always appear in pairs, located on both sides of the critical horizon and moving further apart as the frequency $\omega$ decreases. For timelike circular orbits, we investigate their distribution in the spacetime of BPSs and highlight four representative families of BPS solutions. </p> </div> </dd> <dt> <a name='item10'>[10]</a> <a href ="/abs/2503.16281" title="Abstract" id="2503.16281"> arXiv:2503.16281 </a> [<a href="/pdf/2503.16281" title="Download PDF" id="pdf-2503.16281" aria-labelledby="pdf-2503.16281">pdf</a>, <a href="https://arxiv.org/html/2503.16281v1" title="View HTML" id="html-2503.16281" aria-labelledby="html-2503.16281" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16281" title="Other formats" id="oth-2503.16281" aria-labelledby="oth-2503.16281">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> The First Model-Independent Chromatic Microlensing Search: No Evidence in the Gravitational Wave Catalog of LIGO-Virgo-KAGRA </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Chakraborty,+A">Aniruddha Chakraborty</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Mukherjee,+S">Suvodip Mukherjee</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 14 + 5 (appendix) pages and 6 + 4 (appendix) figures. Submitted to ApJ </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE) </div> <p class='mathjax'> The lensing of Gravitational Waves (GWs) due to intervening matter distribution in the universe can lead to chromatic and achromatic signatures in the wave-optics and geometrical-optics limit respectively. This makes it difficult to model for the unknown mass distribution of the lens and hence requires a model-independent lensing detection technique from GW data. We perform the first model-independent microlensing search in the wave-optics limit on the 80 GW events observed with both the LIGO detectors from the third observation catalog GWTC-3 of LIGO-Virgo-KAGRA using the analysis method $\mu$-\texttt{GLANCE}. These unmodelled searches pick up one plausible candidate $\rm GW190408\_181802$ with a slightly above threshold residual amplitude compared to the residual expected from detector noise. However, exploring the microlensing modulation signatures on this event, we do not find any conclusive evidence of the microlensing signal in the data. With this, we confidently rule out the presence of any statistically significant microlensing signal in the 80 events of GWTC-3 in a model-independent way. </p> </div> </dd> <dt> <a name='item11'>[11]</a> <a href ="/abs/2503.16324" title="Abstract" id="2503.16324"> arXiv:2503.16324 </a> [<a href="/pdf/2503.16324" title="Download PDF" id="pdf-2503.16324" aria-labelledby="pdf-2503.16324">pdf</a>, <a href="https://arxiv.org/html/2503.16324v1" title="View HTML" id="html-2503.16324" aria-labelledby="html-2503.16324" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16324" title="Other formats" id="oth-2503.16324" aria-labelledby="oth-2503.16324">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Natural inflation in Palatini $F(R,X)$ </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Bostan,+N">N. Bostan</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Dejrah,+R">R.H. Dejrah</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Dioguardi,+C">C. Dioguardi</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=A.Racioppi">A.Racioppi</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 14 pages, 5 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> In the context of Palatini gravity, $F(R,X)$ models, with X the inflaton kinetic term, are characterized by the appealing property of generating asymptotically flat inflaton potentials. In this paper, we study the case of a Jordan frame potential which is positive and bounded, specifically, natural inflation. We compute the CMB observables and show that for a wide class of $F(R,X)$ theories, including the quadratic one, natural inflation is still viable. </p> </div> </dd> <dt> <a name='item12'>[12]</a> <a href ="/abs/2503.16377" title="Abstract" id="2503.16377"> arXiv:2503.16377 </a> [<a href="/pdf/2503.16377" title="Download PDF" id="pdf-2503.16377" aria-labelledby="pdf-2503.16377">pdf</a>, <a href="https://arxiv.org/html/2503.16377v1" title="View HTML" id="html-2503.16377" aria-labelledby="html-2503.16377" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16377" title="Other formats" id="oth-2503.16377" aria-labelledby="oth-2503.16377">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Primodial power spectrum in loop quantum cosmology for different regularizations </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Kowalczyk,+M">Maciej Kowalczyk</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Marug%C3%A1n,+G+A+M">Guillermo A. Mena Marug谩n</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Paw%C5%82owski,+T">Tomasz Paw艂owski</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 13 pages, 5 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> In Loop Quantum Cosmology, the quantization of the Hamiltonian constraint involves a regularization procedure which is affected by certain ambiguities. Moreover, different regularizations lead to distinct mathematical formulations and, consequently, to different physical predictions. In this work, we explore the impact of this regularization on the primordial power spectrum of cosmological perturbations. More specifically, we study this power spectrum for the conventional regularization used in Loop Quantum Cosmology and for two alternative prescriptions suggested in the literature. We set initial conditions for the perturbations at the bounce corresponding to a recently proposed vacuum state, optimally adapted to the background dynamics. This choice of vacuum is based on an asymptotic Hamiltonian diagonalization in the ultraviolet sector of the perturbations which provides a non-oscillating power spectrum. Employing a suitable approximation to the propagation equations of the perturbations around the bounce, we are able to obtain an analytic expression for the primordial power spectrum of this vacuum for all the discussed regularizations. We compare the results and prove that the main relevant distinction between the corresponding spectra is the scale where power suppression occurs. The associated wavenumber scale is proportional to the square root of the critical density in Loop Quantum Cosmology, density which is different for each of the studied regularizations. </p> </div> </dd> </dl> <dl id='articles'> <h3>Cross submissions (showing 11 of 11 entries)</h3> <dt> <a name='item13'>[13]</a> <a href ="/abs/2503.15613" title="Abstract" id="2503.15613"> arXiv:2503.15613 </a> (cross-list from astro-ph.HE) [<a href="/pdf/2503.15613" title="Download PDF" id="pdf-2503.15613" aria-labelledby="pdf-2503.15613">pdf</a>, <a href="https://arxiv.org/html/2503.15613v1" title="View HTML" id="html-2503.15613" aria-labelledby="html-2503.15613" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15613" title="Other formats" id="oth-2503.15613" aria-labelledby="oth-2503.15613">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Prompt Periodicity in the GRB 211211A Precursor: Black-hole or magnetar engine? </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Lamb,+G+P">Gavin P. Lamb</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Baxter,+T">Thomas Baxter</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Omand,+C+M+B">Conor M. B. Omand</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Dimple">Dimple</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=McGrath,+Z">Zo毛 McGrath</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Turnbull,+C">Cairns Turnbull</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Burns,+E">Eric Burns</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Hamidani,+H">Hamid Hamidani</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Mandel,+I">Ilya Mandel</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Page,+K+L">Kim L. Page</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Rosswog,+S">Stephan Rosswog</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Sarin,+N">Nikhil Sarin</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Blain,+A">Andrew Blain</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Datrier,+L">Laurence Datrier</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Kobayashi,+S">Shiho Kobayashi</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Levan,+A">Andrew Levan</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Starling,+R">Rhaana Starling</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Gompertz,+B">Benjamin Gompertz</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Habeeb,+N">Nusrin Habeeb</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Nguyen,+K">Khang Nguyen</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Tanvir,+N">Nial Tanvir</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 18 pages,14 figures, submitted to MNRAS </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Astrophysical Phenomena (astro-ph.HE)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The merger origin long GRB 211211A was a class (re-)defining event. A precursor was identified with a $\sim 1$ s separation from the main burst, as well as a claimed candidate quasi-periodic oscillation (QPO) with a frequency $\sim20$ Hz. Here, we explore the implications of the precursor, assuming the quasi-periodicity is real. The precursor variability timescale requires relativistic motion with a Lorentz factor $\Gamma\gtrsim80$, and implies an engine driven jetted outflow. The declining amplitude of the consecutive pulses requires an episodic engine with an `on/off' cycle consistent with the QPO. For a black-hole central engine, the QPO can have its origin in Lense-Thirring precession of the inner disk at $\sim6-9$ $r_g$ (gravitational radii) for a mass $M_\bullet\leq4.5$ M$_{\odot}$, and $\lesssim 7$ $r_g$ for $M_\bullet>4.5$ M$_{\odot}$ and dimensionless spin $\chi\sim 0.3 - 0.9$. Alternatively, at a disk density of $\sim10^{8 - 12}$ g cm$^{-3}$, the required magnetic field strength for a QPO via magnetohydrodynamic effects will be on the order $B\sim10^{12 - 14}$ G. If the central engine is a short lived magnetar or hypermassive neutron star, then a low-frequency QPO can be produced via instabilities within the disk at a radius of $\sim20 - 70$ km, for a disk density $\sim10^{9 - 12}$ g cm$^{-3}$ and magnetic field $\gtrsim10^{13 - 14}$ G. The QPO cannot be coupled to the neutron star spin, as the co-rotation radius is beyond the scale of the disk. Neither engine can be ruled out -- however, we favour an origin for the precursor candidate QPO as early jet-disk coupling for a neutron star -- black hole merger remnant with mass $M_\bullet>4.5$ M$_{\odot}$. </p> </div> </dd> <dt> <a name='item14'>[14]</a> <a href ="/abs/2503.15659" title="Abstract" id="2503.15659"> arXiv:2503.15659 </a> (cross-list from astro-ph.CO) [<a href="/pdf/2503.15659" title="Download PDF" id="pdf-2503.15659" aria-labelledby="pdf-2503.15659">pdf</a>, <a href="https://arxiv.org/html/2503.15659v1" title="View HTML" id="html-2503.15659" aria-labelledby="html-2503.15659" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15659" title="Other formats" id="oth-2503.15659" aria-labelledby="oth-2503.15659">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> A low-redshift preference for an interacting dark energy model </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Zhai,+Y">Yuejia Zhai</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=de+Cesare,+M">Marco de Cesare</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=van+de+Bruck,+C">Carsten van de Bruck</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Di+Valentino,+E">Eleonora Di Valentino</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Wilson-Ewing,+E">Edward Wilson-Ewing</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 16 pages, 4 figures, 2 tables </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Cosmology and Nongalactic Astrophysics (astro-ph.CO)</span>; General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph) </div> <p class='mathjax'> We explore an interacting dark sector model in trace-free Einstein gravity where dark energy has a constant equation of state, $w=-1$, and the energy-momentum transfer potential is proportional to the cold dark matter density. Compared to the standard $\Lambda$CDM model, this scenario introduces a single additional dimensionless parameter, $\epsilon$, which determines the amplitude of the transfer potential. Using a combination of \textit{Planck} 2018 Cosmic Microwave Background (CMB), DESI 2024 Baryon Acoustic Oscillation (BAO), and Pantheon+ Type Ia supernovae (SNIa) data, we derive stringent constraints on the interaction, finding $\epsilon$ to be of the order of $\sim \mathcal{O}(10^{-4})$. While CMB and SNIa data alone do not favor the presence of such an interaction, the inclusion of DESI data introduces a mild $1\sigma$ preference for an energy-momentum transfer from dark matter to dark energy. This preference is primarily driven by low-redshift DESI BAO measurements, which favor a slightly lower total matter density $\Omega_m$ compared to CMB constraints. Although the interaction remains weak and does not significantly alleviate the $H_0$ and $S_8$ tensions, our results highlight the potential role of dark sector interactions in late-time cosmology. </p> </div> </dd> <dt> <a name='item15'>[15]</a> <a href ="/abs/2503.15729" title="Abstract" id="2503.15729"> arXiv:2503.15729 </a> (cross-list from astro-ph.HE) [<a href="/pdf/2503.15729" title="Download PDF" id="pdf-2503.15729" aria-labelledby="pdf-2503.15729">pdf</a>, <a href="https://arxiv.org/html/2503.15729v1" title="View HTML" id="html-2503.15729" aria-labelledby="html-2503.15729" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.15729" title="Other formats" id="oth-2503.15729" aria-labelledby="oth-2503.15729">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Ignition of weak interactions and r-process outflows in super-collapsar accretion disks </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Agarwal,+A">Aman Agarwal</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Siegel,+D+M">Daniel M. Siegel</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Metzger,+B+D">Brian D. Metzger</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Nagele,+C">Chris Nagele</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 25 pages, 16 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Astrophysical Phenomena (astro-ph.HE)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The collapse of rotating massive (~$10 M_\odot$) stars resulting in hyperaccreting black holes (BHs; "collapsars") is a leading model for the central engines of long-duration gamma-ray bursts (GRBs) and a promising source of rapid neutron capture ("r-process") elements. R-process nucleosynthesis in disk outflows requires the accretion flow to self-neutronize. This occurs because of Pauli-blocking at finite electron degeneracy, associated with a critical accretion rate $\dot M > \dot{M}_{\rm ign}$. We analytically examine the assumptions underlying this "ignition threshold" and its possible breakdown with increasing BH mass $M$. Employing three-dimensional general-relativistic magnetohydrodynamic simulations with weak interactions, we explore the physical conditions of collapsar accretion disks with $M$ ~ 80-3000 $M_\odot$ over more than a viscous timescale as they transition through the threshold. There is remarkable agreement between our simulations and the analytic result $\dot{M}_{\rm ign}\propto \alpha^{5/3}M^{4/3}$ for $M$ ~ 3-3000 $M_\odot$. Simulations and analytic analyses consistently show that the largest BHs leading to r-process nucleosynthesis at $\dot{M}_{\rm ign}$ are $\approx 3000 M_\odot$, beyond which self-neutronization ceases, since the disk temperature $T\propto M^{-1/6}$ decreases below the neutron-proton mass difference (~MeV), suppressing the conversion of protons into neutrons. We show that stellar models of ~$250-10^5M_\odot$ can give rise to BHs of $M$ ~30-1000 $M_\odot$ accreting at $\dot M\gtrsim \dot{M}_{\rm ign}$, yielding ~$10-100 M_\odot$ of light and heavy r-process elements per event. These rare but prolific r-process sources in low-metallicity environments are associated with super-kilonovae and likely extremely energetic GRBs. Such signatures may be used to probe Population III stars. </p> </div> </dd> <dt> <a name='item16'>[16]</a> <a href ="/abs/2503.16132" title="Abstract" id="2503.16132"> arXiv:2503.16132 </a> (cross-list from astro-ph.CO) [<a href="/pdf/2503.16132" title="Download PDF" id="pdf-2503.16132" aria-labelledby="pdf-2503.16132">pdf</a>, <a href="https://arxiv.org/html/2503.16132v1" title="View HTML" id="html-2503.16132" aria-labelledby="html-2503.16132" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16132" title="Other formats" id="oth-2503.16132" aria-labelledby="oth-2503.16132">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Testing f (R) gravity models with DESI-BAO and other cosmological data </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Plaza,+F">Francisco Plaza</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Kraiselburd,+L">Lucila Kraiselburd</a></div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Cosmology and Nongalactic Astrophysics (astro-ph.CO)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> In this paper, we conduct a statistical analysis of various cosmological models within the framework of f (R) gravity theories, motivated by persistent challenges in modern cosmology, such as the unknown mechanisms driving the late-time accelerated expansion of the universe. We begin by presenting a comprehensive formulation of these theories and discussing their potential to resolve the outstanding issues. Following this, we perform a detailed statistical examination in a cosmological context, leveraging a wide array of observational data. Special attention is given to the incorporation of the latest Baryon Acoustic Oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) and of the Pantheon++SH0ES compilation, which play a critical role in constraining these models. Our results show an increase in the values of the distortion parameter b and of the Hubble parameter H0 estimates, due to the use of this new compilation of SnIa data. However, no major changes are perceived when using the DESI data set instead of the previous BAO observations. </p> </div> </dd> <dt> <a name='item17'>[17]</a> <a href ="/abs/2503.16198" title="Abstract" id="2503.16198"> arXiv:2503.16198 </a> (cross-list from quant-ph) [<a href="/pdf/2503.16198" title="Download PDF" id="pdf-2503.16198" aria-labelledby="pdf-2503.16198">pdf</a>, <a href="https://arxiv.org/html/2503.16198v1" title="View HTML" id="html-2503.16198" aria-labelledby="html-2503.16198" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16198" title="Other formats" id="oth-2503.16198" aria-labelledby="oth-2503.16198">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Probing classical and quantum violations of the equivalence of active and passive gravitational mass </div> <div class='list-authors'><a href="https://arxiv.org/search/quant-ph?searchtype=author&query=Fragkos,+V">Vasileios Fragkos</a>, <a href="https://arxiv.org/search/quant-ph?searchtype=author&query=Pikovski,+I">Igor Pikovski</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 13 pages, 5 figures, 2 tables </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Quantum Physics (quant-ph)</span>; General Relativity and Quantum Cosmology (gr-qc); Atomic Physics (physics.atom-ph) </div> <p class='mathjax'> The equivalence of active and passive (EAP) gravitational mass is one of the most fundamental principles of gravity. But in contrast to the usual equivalence of inertial and (passive) gravitational mass, the EAP has not received much attention. Here we revisit this principle and show how it can be used to probe quantum gravity in laboratory-based experiments. We first examine how the dynamics under EAP violations affects classical systems and show that new laboratory tests can be performed, to improve over the current experimental bounds and to test new manifestations of EAP violations. We then extend the analysis to the quantum domain, where quantized energy contributes to mass and the EAP principle can thus shed light on how quantum source masses would gravitate. We show that experiments with cold polar molecules, and future experiments with nuclear atomic clocks, can test the quantum EAP in a regime where quantum gravity phenomenology could become relevant. Our results open new opportunities for fundamental tests of gravity in high-precision laboratory experiments that can shed light on foundational principles of gravity and its interface with quantum theory. </p> </div> </dd> <dt> <a name='item18'>[18]</a> <a href ="/abs/2503.16246" title="Abstract" id="2503.16246"> arXiv:2503.16246 </a> (cross-list from math.DG) [<a href="/pdf/2503.16246" title="Download PDF" id="pdf-2503.16246" aria-labelledby="pdf-2503.16246">pdf</a>, <a href="https://arxiv.org/html/2503.16246v1" title="View HTML" id="html-2503.16246" aria-labelledby="html-2503.16246" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16246" title="Other formats" id="oth-2503.16246" aria-labelledby="oth-2503.16246">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Stability of Positive Mass Theorem for Static Quasi-Local Energy of Compact (Locally) Hyperbolic Graphical Manifolds </div> <div class='list-authors'><a href="https://arxiv.org/search/math?searchtype=author&query=Alaee,+A">Aghil Alaee</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Liu,+J">Jiusen Liu</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 13 pages, comments are welcome! </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Differential Geometry (math.DG)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> In this paper, we consider compact graphical manifolds with boundary over (locally) hyperbolic static space. We prove the stability of the positive mass theorem with respect to the Federer--Fleming flat distance for the static quasi-local Brown-York energy of the outer boundary of compact (locally) hyperbolic graphical manifolds. </p> </div> </dd> <dt> <a name='item19'>[19]</a> <a href ="/abs/2503.16253" title="Abstract" id="2503.16253"> arXiv:2503.16253 </a> (cross-list from astro-ph.HE) [<a href="/pdf/2503.16253" title="Download PDF" id="pdf-2503.16253" aria-labelledby="pdf-2503.16253">pdf</a>, <a href="https://arxiv.org/html/2503.16253v1" title="View HTML" id="html-2503.16253" aria-labelledby="html-2503.16253" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16253" title="Other formats" id="oth-2503.16253" aria-labelledby="oth-2503.16253">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Superluminal Dark Photons as a Solution to the GRB 221009A Anomaly </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Valamontes,+A">Antonios Valamontes</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Markoulakis,+E">Emmanuel Markoulakis</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Adamopoulos,+I">Ioannis Adamopoulos</a></div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Astrophysical Phenomena (astro-ph.HE)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The detection of exceptionally high-energy {\gamma}-photons (up to 18 TeV) from GRB 221009A by the LHAASO Collaboration challenges conventional physics. Photon-axion-like particle (ALP) oscillations have been proposed to explain this anomaly, but they rely on specific parameter tuning. We present an alternative explanation involving superluminal dark photons. Building on the frameworks of Markoulakis and Valamontes, we propose that dark photons facilitated faster-than-light (FTL) propagation of information, allowing {\gamma}-photons to bypass extragalactic background light (EBL) attenuation. This hypothesis aligns with cosmological observations and experimental results, including those from the LHC, providing a robust framework for addressing the GRB 221009A anomaly. </p> </div> </dd> <dt> <a name='item20'>[20]</a> <a href ="/abs/2503.16272" title="Abstract" id="2503.16272"> arXiv:2503.16272 </a> (cross-list from astro-ph.CO) [<a href="/pdf/2503.16272" title="Download PDF" id="pdf-2503.16272" aria-labelledby="pdf-2503.16272">pdf</a>, <a href="https://arxiv.org/html/2503.16272v1" title="View HTML" id="html-2503.16272" aria-labelledby="html-2503.16272" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16272" title="Other formats" id="oth-2503.16272" aria-labelledby="oth-2503.16272">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Thermodynamics of sign-switching dark energy models </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Tamayo,+D">David Tamayo</a></div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Cosmology and Nongalactic Astrophysics (astro-ph.CO)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> We perform a comprehensive thermodynamic analysis of three sign-switching dark energy models in a flat FLRW cosmology: graduated dark energy (gDE), sign-switching cosmological constant ($\Lambda_s$), and smoothed sign-switching cosmological constant ($\Lambda_t$). We systematically derive key cosmological thermodynamic quantities -- horizon temperature, horizon entropy, internal entropy, total entropy, and their first and second derivatives -- using the Generalised Second Law (GSL) as the fundamental evaluation criterion. We first confirm the compliance of the $\Lambda$CDM model with the GSL, establishing a baseline for comparison. We find that despite their unconventional negative-to-positive energy density transitions, both $\Lambda_s$ and $\Lambda_t$ remain thermodynamically consistent. In contrast, gDE exhibits significant issues: divergences in its equation-of-state lead to infinite horizon temperature and entropy derivatives; and asymptotically, the horizon temperature diverges while entropy approaches zero, causing entropy reduction and violating the GSL. We highlight a key insight: models with divergences in the product of the dark energy equation-of-state parameter and its energy density ($w_x \Omega_x$) inevitably produce thermodynamic inconsistencies in standard cosmology. This thermodynamic approach provides a complementary criterion alongside observational constraints for evaluating the physical viability of cosmological models. </p> </div> </dd> <dt> <a name='item21'>[21]</a> <a href ="/abs/2503.16317" title="Abstract" id="2503.16317"> arXiv:2503.16317 </a> (cross-list from astro-ph.HE) [<a href="/pdf/2503.16317" title="Download PDF" id="pdf-2503.16317" aria-labelledby="pdf-2503.16317">pdf</a>, <a href="https://arxiv.org/html/2503.16317v1" title="View HTML" id="html-2503.16317" aria-labelledby="html-2503.16317" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16317" title="Other formats" id="oth-2503.16317" aria-labelledby="oth-2503.16317">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Proto-neutron star oscillations including accretion flows </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Tseneklidou,+D">Dimitra Tseneklidou</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Luna,+R">Raimon Luna</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Cerd%C3%A1-Dur%C3%A1n,+P">Pablo Cerd谩-Dur谩n</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Torres-Forn%C3%A9,+A">Alejandro Torres-Forn茅</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 23 pages, 10 figures, submitted to PRD </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Astrophysical Phenomena (astro-ph.HE)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The gravitational wave signature from core-collapse supernovae (CCSNe) is dominated by quadrupolar oscillation modes of the newly born proto-neutron star (PNS), and could be detectable at galactic distances. We have developed a framework for computing the normal oscillation modes of a PNS in general relativity, including, for the first time, the presence of an accretion flow and a surrounding stalled accretion shock. These new ingredients are key to understand PNS oscillation modes, in particular those related to the standing-accretion-shock instability (SASI). Their incorporation is an important step towards accurate PNS asteroseismology. For this purpose, we perform linear and adiabatic perturbations of a spherically symmetric background, in the relativistic Cowling approximation, and cast the resulting equations as an eigenvalue problem. We discretize the eigenvalue problem using collocation Chebyshev spectral methods, which is then solved by means of standard and efficient linear algebra methods. We impose boundary conditions at the accretion shock compatible with the Rankine-Hugoniot conditions. We present several numerical examples to assess the accuracy and convergence of the numerical code, as well as to understand the effect of an accretion flow on the oscillation modes, as a stepping stone towards a complete analysis of the CCSNe case. </p> </div> </dd> <dt> <a name='item22'>[22]</a> <a href ="/abs/2503.16415" title="Abstract" id="2503.16415"> arXiv:2503.16415 </a> (cross-list from astro-ph.CO) [<a href="/pdf/2503.16415" title="Download PDF" id="pdf-2503.16415" aria-labelledby="pdf-2503.16415">pdf</a>, <a href="https://arxiv.org/html/2503.16415v1" title="View HTML" id="html-2503.16415" aria-labelledby="html-2503.16415" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16415" title="Other formats" id="oth-2503.16415" aria-labelledby="oth-2503.16415">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Apparent $w<-1$ and a Lower $S_8$ from Dark Axion and Dark Baryons Interactions </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Khoury,+J">Justin Khoury</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Lin,+M">Meng-Xiang Lin</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Trodden,+M">Mark Trodden</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 8 pages, 4 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Cosmology and Nongalactic Astrophysics (astro-ph.CO)</span>; General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th) </div> <p class='mathjax'> We show that a simple coupling between dark energy and dark matter can simultaneously address two distinct hints at new physics coming from cosmological observations. The first is the recent evidence from the DESI project and supernovae observations that the dark energy equation of state~$w$ is evolving over cosmic time from an earlier value that is~$<-1$ to a present-day value~$>-1$. The second observation is the so-called~$S_8$ tension, describing the suppression of the growth of matter overdensities compared to that expected in the~$\Lambda$CDM model. We propose a stable, technically natural particle physics implementation of this idea, in which dark matter consists of dark baryons in a strongly-coupled hidden sector, and the dark energy field is the associated dark axion. The time-variation of the dark matter mass results in an effective dark energy equation of state that exhibits a phantom crossing behavior consistent with recent results. It also results in a slight delay in matter-radiation equality, which suppresses the overall growth of density perturbations. </p> </div> </dd> <dt> <a name='item23'>[23]</a> <a href ="/abs/2503.16427" title="Abstract" id="2503.16427"> arXiv:2503.16427 </a> (cross-list from hep-th) [<a href="/pdf/2503.16427" title="Download PDF" id="pdf-2503.16427" aria-labelledby="pdf-2503.16427">pdf</a>, <a href="https://arxiv.org/html/2503.16427v1" title="View HTML" id="html-2503.16427" aria-labelledby="html-2503.16427" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.16427" title="Other formats" id="oth-2503.16427" aria-labelledby="oth-2503.16427">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> On the Holographic Dual of a Symmetry Operator at Finite Temperature </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Heckman,+J+J">Jonathan J. Heckman</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=H%C3%BCbner,+M">Max H眉bner</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Murdia,+C">Chitraang Murdia</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 12 pages + appendices, 4 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> Topological symmetry operators of holographic large $N$ CFT$_D$'s are dual to dynamical branes in the gravity dual AdS$_{D+1}$. We use this correspondence to establish a dictionary between thermal expectation values of symmetry operators in the Euclidean CFT$_D$ and the evaluation of gravitational saddles in the presence of a dynamical brane. Expectation values of $0$-form symmetry operators in the CFT$_D$ are then related to branes wrapped on volume minimizing cycles in the bulk, i.e., the Euclidean continuation of a black hole horizon. We illustrate with some representative examples, including gravity in AdS$_3$, duality / triality defects in 4D $\mathcal{N} = 4$ Super Yang-Mills theory, and the dual of R-symmetry operators probing 5D BPS black holes. </p> </div> </dd> </dl> <dl id='articles'> <h3>Replacement submissions (showing 22 of 22 entries)</h3> <dt> <a name='item24'>[24]</a> <a href ="/abs/2312.03070" title="Abstract" id="2312.03070"> arXiv:2312.03070 </a> (replaced) [<a href="/pdf/2312.03070" title="Download PDF" id="pdf-2312.03070" aria-labelledby="pdf-2312.03070">pdf</a>, <a href="https://arxiv.org/html/2312.03070v2" title="View HTML" id="html-2312.03070" aria-labelledby="html-2312.03070" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2312.03070" title="Other formats" id="oth-2312.03070" aria-labelledby="oth-2312.03070">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Rescuing the Unruh Effect in Lorentz Violating Gravity </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Del+Porro,+F">F. Del Porro</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Herrero-Valea,+M">M. Herrero-Valea</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Liberati,+S">S. Liberati</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Schneider,+M">M. Schneider</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 34 pages, 6 figures, identical with published version </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; High Energy Physics - Theory (hep-th) </div> <p class='mathjax'> While the robustness of Hawking radiation in the presence of UV Lorentz breaking is well-established, the Unruh effect has posed a challenge, with a large literature concluding that even the low-energy restoration of Lorentz invariance may not be sufficient to sustain this phenomenon. Notably, these previous studies have primarily focused on Lorentz-breaking matter on a conventional Rindler wedge. In this work, we demonstrate that considering the complete structure of Lorentz-breaking gravity, specifically the presence of a hypersurface orthogonal aether field, leads to the selection of a new Rindler wedge configuration characterized by a uniformly accelerated aether flow. This uniform acceleration provides a reference scale for comparison with the Lorentz-breaking one, thus ensuring the persistence of the Unruh effect in this context. We establish this by calculating the expected temperature using a Bogolubov approach, and by analyzing the response of a uniformly accelerated detector. We suggest that this resilience of the Unruh effect opens interesting possibilities towards future developments for using it as a tool to constrain Lorentz breaking theories of gravity. </p> </div> </dd> <dt> <a name='item25'>[25]</a> <a href ="/abs/2407.17203" title="Abstract" id="2407.17203"> arXiv:2407.17203 </a> (replaced) [<a href="/pdf/2407.17203" title="Download PDF" id="pdf-2407.17203" aria-labelledby="pdf-2407.17203">pdf</a>, <a href="https://arxiv.org/html/2407.17203v2" title="View HTML" id="html-2407.17203" aria-labelledby="html-2407.17203" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2407.17203" title="Other formats" id="oth-2407.17203" aria-labelledby="oth-2407.17203">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> The M枚bius Game: A Quantum-Inspired Test of General Relativity </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Tselentis,+E">Eleftherios-Ermis Tselentis</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Baumeler,+%C3%84">脛min Baumeler</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 6 pages, 4 figures, short version of <a href="https://arxiv.org/abs/2309.15752" data-arxiv-id="2309.15752" class="link-https">arXiv:2309.15752</a> [qr-qc], references added, improved presentation </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; Quantum Physics (quant-ph) </div> <p class='mathjax'> We present a tight inequality to test the dynamical nature of spacetime. A general-relativistic violation of that inequality certifies change of curvature, in the same sense as a quantum-mechanical violation of a Bell inequality certifies a source of entanglement. The inequality arises from a minimal generalization of the Bell setup. It represents a limit on the winning chance of a collaborative multi-agent game played on the M枚bius graph. A long version of this Letter including other games and how these games certify the dynamical character of the celebrated quantum switch is accessible as <a href="https://arxiv.org/abs/2309.15752" data-arxiv-id="2309.15752" class="link-https">arXiv:2309.15752</a> [gr-qc]. </p> </div> </dd> <dt> <a name='item26'>[26]</a> <a href ="/abs/2408.13594" title="Abstract" id="2408.13594"> arXiv:2408.13594 </a> (replaced) [<a href="/pdf/2408.13594" title="Download PDF" id="pdf-2408.13594" aria-labelledby="pdf-2408.13594">pdf</a>, <a href="https://arxiv.org/html/2408.13594v2" title="View HTML" id="html-2408.13594" aria-labelledby="html-2408.13594" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2408.13594" title="Other formats" id="oth-2408.13594" aria-labelledby="oth-2408.13594">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Matter really does matter, or Why $f(R,{\rm Matter})$ type theories are significant for gravitational physics and cosmology </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Harko,+T">Tiberiu Harko</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Pinto,+M+A+S">Miguel A. S. Pinto</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Shahidi,+S">Shahab Shahidi</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 20 pages, 3 figures </div> <div class='list-journal-ref'><span class='descriptor'>Journal-ref:</span> Phys. Dark Univ. 48 (2025) 101863 </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th) </div> <p class='mathjax'> In a recent paper (Lacombe, Mukohyama, and Seitz, JCAP {\bf 2024}, 05, 064 (2024)), the authors provided an in-depth analysis of a class of modified gravity theories, generally called $f(R,{\rm Matter})$ theories, which assume the existence of a non-minimal coupling between geometry and matter. It was argued that if the matter sector consists of Standard Model particles, then these theories suffer from the presence of ghosts, or are just scalar/vector-tensor theories. Hence, the relevance of these theories for cosmology was questioned. It is the goal of the present work to carefully analyze, discuss, and assess the line of arguments proposed in Lacombe et al. JCAP {\bf 2024}, 05, 064 (2024). After a qualitative critical discussion of the five general arguments proposed for the validity of a gravitational theory, we present the theoretical foundations of the $f(R,{\rm Matter})$ theories, including their possible relations with quantum gravity, and discuss in detail the role of matter. The matter source discussed in Lacombe et al., consisting predominantly of a massless scalar field, is extremely restrictive, and rather irrelevant for cosmology and the description of the observational data. We also devote a detailed discussion of the problem of the energy scales of the $f(R,{\rm Matter})$ theories. To test the observational relevance of this type of theories we present the comparison of a simple theoretical model with a small set of observational data and with the $\Lambda$CDM paradigm. We conclude by pointing out that the analysis of Lacombe et al., JCAP {\bf 2024}, 05, 064 (2024), even very useful for the understanding of some limited aspects of the $f(R,{\rm Matter})$ theories, and of their theoretical foundations, cannot be considered as a valid or definite criticism of these approaches to gravity. </p> </div> </dd> <dt> <a name='item27'>[27]</a> <a href ="/abs/2410.06563" title="Abstract" id="2410.06563"> arXiv:2410.06563 </a> (replaced) [<a href="/pdf/2410.06563" title="Download PDF" id="pdf-2410.06563" aria-labelledby="pdf-2410.06563">pdf</a>, <a href="https://arxiv.org/html/2410.06563v2" title="View HTML" id="html-2410.06563" aria-labelledby="html-2410.06563" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2410.06563" title="Other formats" id="oth-2410.06563" aria-labelledby="oth-2410.06563">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Self interacting scalar field theory in general curved spacetimes at zero and finite temperature revisited </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Nath,+V">Vishal Nath</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Bhattacharya,+S">Sourav Bhattacharya</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> v2; 37pp, 16 figs; added references, discussions and many clarifications; improved presentation; accepted in PRD </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; High Energy Physics - Theory (hep-th) </div> <p class='mathjax'> We revisit the problem of spontaneous symmetry breaking (SSB), its restoration, and phase transition for a self interacting quantum scalar field in a general curved background, at zero and finite temperature. To the best of our knowledge, most of the earlier computations in this context have been done in the linear order in curvature, which may not be very suitable for the Ricci flat spacetimes. One of our objectives is to see whether the higher order terms can bring in qualitatively new physical effects, and thereby attempting to fill in this gap in the literature. We use Bunch and Parker's local momentum space representation of the Schwinger-DeWitt expansion of the Feynman propagator. Such expansion, being based upon the local Lorentz symmetry of spacetime, essentially probes the leading curvature correction to short scale, ultraviolet quantum processes. We compute the renormalised, background spacetime curvature (up to quadratic order) and temperature dependent one loop effective potential for $\phi^4$ plus $\phi^3$ self interaction. In particular for the de Sitter spacetime, we have shown for the $\phi^4$-theory that we can have SSB even with a positive rest mass squared and positive non-minimal coupling, at zero temperature. This cannot be achieved by the linear curvature term alone and the result remains valid for a very large range of renormalisation scale. Such SSB will generate a field mass that depends upon the spacetime curvature as well as the non-minimal coupling. For a phase transition, we have computed the leading curvature correction to the critical temperature. At finite temperature, symmetry restoration is demonstrated. We also extend some of the above results to two loop level. The symmetry breaking in de Sitter at two loop remains present. We have further motivated the necessity of treating this problem non-perturbatively in some instances. </p> </div> </dd> <dt> <a name='item28'>[28]</a> <a href ="/abs/2410.17056" title="Abstract" id="2410.17056"> arXiv:2410.17056 </a> (replaced) [<a href="/pdf/2410.17056" title="Download PDF" id="pdf-2410.17056" aria-labelledby="pdf-2410.17056">pdf</a>, <a href="https://arxiv.org/html/2410.17056v2" title="View HTML" id="html-2410.17056" aria-labelledby="html-2410.17056" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2410.17056" title="Other formats" id="oth-2410.17056" aria-labelledby="oth-2410.17056">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Reconstructing the LISA massive black hole binary population via iterative kernel density estimation </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Sadiq,+J">Jam Sadiq</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Dey,+K">Kallol Dey</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Dent,+T">Thomas Dent</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Barausse,+E">Enrico Barausse</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 17 pages, 11 figures </div> <div class='list-journal-ref'><span class='descriptor'>Journal-ref:</span> Phys. Rev. D 111, 063051 (2025) </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; Cosmology and Nongalactic Astrophysics (astro-ph.CO) </div> <p class='mathjax'> Reconstructing the properties of the astrophysical population of binary compact objects in the universe is a key science goal of gravitational wave detectors. This goal is hindered by the finite strain, frequency sensitivity and observing time of current and future detectors. This implies that we can in general observe only a selected subset of the underlying population, with limited event statistics, and also nontrivial observational uncertainties in the parameters of each event. In this work, we will focus on observations of massive black hole binaries with the Laser Interferometer Space Antenna (LISA). If these black holes grow from population III star remnants (``light seeds''), a significant fraction of the binary population at low masses and high redshift will be beyond LISA's observational reach; thus, selection effects have to be accounted for when reconstructing the underlying population. Here we propose an iterative, kernel density estimation (KDE)-based non-parametric method, in order to tackle these statistical challenges in reconstructing the astrophysical population distribution from a finite number of observed signals over total mass and redshift. We test the method against a set of simulated LISA observations in a light seed formation scenario. We find that our approach is successful at reconstructing the underlying astrophysical distribution in mass and redshift, except in parameter regions where zero or order(1) signals are observed. </p> </div> </dd> <dt> <a name='item29'>[29]</a> <a href ="/abs/2412.15395" title="Abstract" id="2412.15395"> arXiv:2412.15395 </a> (replaced) [<a href="/pdf/2412.15395" title="Download PDF" id="pdf-2412.15395" aria-labelledby="pdf-2412.15395">pdf</a>, <a href="https://arxiv.org/html/2412.15395v2" title="View HTML" id="html-2412.15395" aria-labelledby="html-2412.15395" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2412.15395" title="Other formats" id="oth-2412.15395" aria-labelledby="oth-2412.15395">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Stealth black holes in Aether Scalar Tensor theory </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Skordis,+C">Constantinos Skordis</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Vokrouhlicky,+D+M+J">David M. J. Vokrouhlicky</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 30 pages, 1 table, some typos corrected, matches published version </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE) </div> <p class='mathjax'> The Aether Scalar Tensor (AeST) theory is an extension of general relativity(GR) successful at reproducing galactic rotational curves, gravitational lensing, linear large scale structure and cosmic microwave background power spectrum observations. We solve the most general static spherically symmetric vacuum equations in the strong-field regime of AeST and find two classes of stealth black hole solutions -- those with exact GR geometries -- containing non-trivial secondary hair. In particular, one of these can be continuously joined to the cosmological solution of AeST. We also derive a non-black hole solution with zero spatial component in the vector field. This result proves the existence of mathematically and observationally consistent candidates for black holes in AeST, and creates a basis for testing the theory in the strong-field regime. </p> </div> </dd> <dt> <a name='item30'>[30]</a> <a href ="/abs/2412.20592" title="Abstract" id="2412.20592"> arXiv:2412.20592 </a> (replaced) [<a href="/pdf/2412.20592" title="Download PDF" id="pdf-2412.20592" aria-labelledby="pdf-2412.20592">pdf</a>, <a href="/format/2412.20592" title="Other formats" id="oth-2412.20592" aria-labelledby="oth-2412.20592">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> The Hamilton equations in $f(T)$ teleparallel gravity and in New General Relativity </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Bajardi,+F">Francesco Bajardi</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Blixt,+D">Daniel Blixt</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Capozziello,+S">Salvatore Capozziello</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 30 pages; Accepted for publication in Physical Review D </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span>; High Energy Physics - Theory (hep-th) </div> <p class='mathjax'> We derive the Hamiltonian function for extended teleparallel theories of gravity in their covariant formulation. In particular, we present the Hamiltonian for $f(T)$ gravity and New General Relativity. From this, we obtain the related Hamilton equations, which are presented both in covariant formulation and Weitzenb枚ck gauge. In this framework, teleparallel equivalent to General Relativity, its $f(T)$ extension and New General Relativity can be compared. We find that $f(T)$ and New General Relativity consistently reduce to the Teleparallel Equivalent to General Relativity, while significant differences appear comparing the Hamilton equations of $f(T)$ with $f(R)$ gravity. </p> </div> </dd> <dt> <a name='item31'>[31]</a> <a href ="/abs/2503.08424" title="Abstract" id="2503.08424"> arXiv:2503.08424 </a> (replaced) [<a href="/pdf/2503.08424" title="Download PDF" id="pdf-2503.08424" aria-labelledby="pdf-2503.08424">pdf</a>, <a href="https://arxiv.org/html/2503.08424v3" title="View HTML" id="html-2503.08424" aria-labelledby="html-2503.08424" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2503.08424" title="Other formats" id="oth-2503.08424" aria-labelledby="oth-2503.08424">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Thin accretion disk around Schwarzschild-like black hole in bumblebee gravity </div> <div class='list-authors'><a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Cai,+Z">Ziqiang Cai</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Ban,+Z">Zhenglong Ban</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Feng,+H">Haiyuan Feng</a>, <a href="https://arxiv.org/search/gr-qc?searchtype=author&query=Yang,+J">Jinsong Yang</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 15 pages, 13 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">General Relativity and Quantum Cosmology (gr-qc)</span> </div> <p class='mathjax'> We investigate the physical properties and the optical appearance of a thin accretion disk surrounding a Schwarzschild-like black hole (BH) within the framework of bumblebee gravity. We study the impact of the Lorentz symmetry breaking (LSB) parameter on various aspects of the disk, including its energy flux, temperature distribution, and emission spectrum. By deriving and analyzing both direct and secondary images of the accretion disk, we examine how the observational inclination angle and the LSB parameter affect image profile. We calculate and plot the distributions of both redshift and observed flux for the disk as seen by distant observers at different inclination angles. Our findings indicate that those distributions are influenced not only by the LSB parameter but also the observer's inclination angle. </p> </div> </dd> <dt> <a name='item32'>[32]</a> <a href ="/abs/2202.12762" title="Abstract" id="2202.12762"> arXiv:2202.12762 </a> (replaced) [<a href="/pdf/2202.12762" title="Download PDF" id="pdf-2202.12762" aria-labelledby="pdf-2202.12762">pdf</a>, <a href="https://arxiv.org/html/2202.12762v2" title="View HTML" id="html-2202.12762" aria-labelledby="html-2202.12762" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2202.12762" title="Other formats" id="oth-2202.12762" aria-labelledby="oth-2202.12762">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Parameter Estimation with Nonstationary Noise in Gravitational-wave Data </div> <div class='list-authors'><a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Kumar,+S">Sumit Kumar</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Nitz,+A+H">Alexander H. Nitz</a>, <a href="https://arxiv.org/search/astro-ph?searchtype=author&query=Forteza,+X+J">Xisco Jim茅nez Forteza</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 15 pages, 5 figures, and 2 tables, Matches with the journal version </div> <div class='list-journal-ref'><span class='descriptor'>Journal-ref:</span> 2025 ApJ 982 67 </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Instrumentation and Methods for Astrophysics (astro-ph.IM)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The sensitivity of gravitational-wave (GW) detectors is characterized by their noise curves, which determine the detector's reach and ability to measure the parameters of astrophysical sources accurately. The detector noise is typically modeled as stationary and Gaussian for many practical purposes and is characterized by its Power Spectral Density (PSD). However, due to environmental and instrumental factors, physical changes in the state of detectors may introduce non-stationarity into the noise. Misestimation of the noise behavior directly impacts the posterior width of the signal parameters. It becomes an issue for studies that depend on accurate localization volumes, such as i) probing cosmological parameters (e.g., Hubble constant) using cross-correlation methods with galaxies, ii) doing electromagnetic follow-up using localization information from parameter estimation (PE) done from pre-merger data. We study the effects of dynamical noise on the PE of the GW events. We develop a new method to correct dynamical noise by estimating a locally valid pseudo-PSD normalized along a potential signal's time-frequency track. We do simulations by injecting binary neutron star (BNS) merger signals in various scenarios where the detector goes through a period of non-stationarity with reference noise curves of third-generation detectors (Cosmic Explorer, Einstein telescope). As an example, for a source where mis-modeling of the noise biases the signal-to-noise estimate by even $10\%$, one would expect the estimated sky localization to be either under or over-reported by $\sim 20\%$; errors like this, especially in low-latency, could potentially cause follow-up campaigns to miss the actual source location. </p> </div> </dd> <dt> <a name='item33'>[33]</a> <a href ="/abs/2309.03421" title="Abstract" id="2309.03421"> arXiv:2309.03421 </a> (replaced) [<a href="/pdf/2309.03421" title="Download PDF" id="pdf-2309.03421" aria-labelledby="pdf-2309.03421">pdf</a>, <a href="/format/2309.03421" title="Other formats" id="oth-2309.03421" aria-labelledby="oth-2309.03421">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Genericity of singularities in spacetimes with weakly trapped submanifolds </div> <div class='list-authors'><a href="https://arxiv.org/search/math?searchtype=author&query=Silva,+I+P+C+e">Ivan Pontual Costa e Silva</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Espinoza,+V+L">Victor Luis Espinoza</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> Preprint was revised and expanded in <a href="https://arxiv.org/abs/2406.09651" data-arxiv-id="2406.09651" class="link-https">arXiv:2406.09651</a> </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Differential Geometry (math.DG)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> Using the standard Whitney topologies on spaces of Lorentzian metrics, we show that the existence of causal incomplete geodesics is a $C^\infty$-generic feature within the class of spacetimes of a given dimension $n\geq 3$ that are stably causal, satisfy the timelike convergence condition (``strong energy condition'') and contain a codimension-two spacelike weakly trapped closed submanifold such as, e.g., a marginally outer trapped surface (MOTS). By using a singularity theorem of Galloway and Senovilla for spacetimes containing trapped closed submanifolds of codimension higher than two we also prove an analogous $C^\infty$-genericity result for stably causal spacetimes with a suitably modified curvature condition and weakly trapped closed spacelike submanifold of any codimension $k> 2$. </p> </div> </dd> <dt> <a name='item34'>[34]</a> <a href ="/abs/2312.05224" title="Abstract" id="2312.05224"> arXiv:2312.05224 </a> (replaced) [<a href="/pdf/2312.05224" title="Download PDF" id="pdf-2312.05224" aria-labelledby="pdf-2312.05224">pdf</a>, <a href="https://arxiv.org/html/2312.05224v3" title="View HTML" id="html-2312.05224" aria-labelledby="html-2312.05224" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2312.05224" title="Other formats" id="oth-2312.05224" aria-labelledby="oth-2312.05224">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Poincar茅 Duality for Supermanifolds, Higher Cartan Structures and Geometric Supergravity </div> <div class='list-authors'><a href="https://arxiv.org/search/math-ph?searchtype=author&query=Eder,+K">Konstantin Eder</a>, <a href="https://arxiv.org/search/math-ph?searchtype=author&query=Huerta,+J">John Huerta</a>, <a href="https://arxiv.org/search/math-ph?searchtype=author&query=Noja,+S">Simone Noja</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> Several new results, significantly improved exposition and references included, 45 pages. Comments are welcome! </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Mathematical Physics (math-ph)</span>; General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Algebraic Geometry (math.AG); Differential Geometry (math.DG) </div> <p class='mathjax'> We study relative differential and integral forms on families of supermanifolds and investigate their cohomology. In particular, we establish a relative version of Poincar茅-Verdier duality, relating the cohomology of differential and integral forms, and provide a concrete interpretation via Berezin fiber integration, which we introduce. To complement Poincar茅 duality, we prove compactly supported Poincar茅 lemmas for both differential and integral forms, filling a gap in the literature. We then apply our results to the mathematical foundations of supergravity. Specifically, we rigorously define picture-changing operators via relative Poincar茅 duality and use them to formulate a general action principle for geometric supergravity in a mathematically rigorous manner. As an example, we explicitly describe three-dimensional supergravity via higher Cartan structures, which are defined by certain classes of connections valued in $L_\infty$-superalgebras. Our construction provides a unified framework interpolating between two equivalent formulations of supergravity in the physics literature: the superspace approach and the group manifold approach. </p> </div> </dd> <dt> <a name='item35'>[35]</a> <a href ="/abs/2406.09651" title="Abstract" id="2406.09651"> arXiv:2406.09651 </a> (replaced) [<a href="/pdf/2406.09651" title="Download PDF" id="pdf-2406.09651" aria-labelledby="pdf-2406.09651">pdf</a>, <a href="https://arxiv.org/html/2406.09651v2" title="View HTML" id="html-2406.09651" aria-labelledby="html-2406.09651" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2406.09651" title="Other formats" id="oth-2406.09651" aria-labelledby="oth-2406.09651">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> On the genericity of singularities in spacetimes with weakly trapped submanifolds </div> <div class='list-authors'><a href="https://arxiv.org/search/math?searchtype=author&query=Espinoza,+V+L">Victor Luis Espinoza</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Silva,+I+P+C+e">Ivan Pontual Costa e Silva</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> arXiv admin note: substantial text overlap with <a href="https://arxiv.org/abs/2309.03421" data-arxiv-id="2309.03421" class="link-https">arXiv:2309.03421</a> </div> <div class='list-journal-ref'><span class='descriptor'>Journal-ref:</span> J. Math. Phys. 66, 032501 (2025) </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Differential Geometry (math.DG)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> We investigate suitable, physically motivated conditions on spacetimes containing certain submanifolds - the so-called {weakly trapped submanifolds} - that ensure, in a set of neighboring metrics with respect to a convenient topology, that the phenomenon of nonspacelike geodesic incompleteness (i.e., the existence of singularities) is generic in a precise technical sense. We obtain two sets of results. First, we use strong Whitney topologies on spaces of Lorentzian metrics on a manifold $M$, in the spirit of Lerner and obtain that while the set of singular Lorentzian metrics around a fiducial one possessing a weakly trapped submanifold $\Sigma$ is not really generic, it is nevertheless prevalent in a sense we define, and thus still quite ``large'' in this sense. We prove versions of that result both for the case when $\Sigma$ has codimension 2, and for the case of higher codimension. <br>The second set of results explore a similar question, but now for initial data sets containing MOTS. For this case, we use certain well-known infinite dimensional, Hilbert manifold structures on the space of initial data and use abstract functional-analytic methods based on the work of Biliotti, Javaloyes, and Piccione to obtain a true genericity of null geodesic incompleteness around suitable initial data sets containing MOTS. </p> </div> </dd> <dt> <a name='item36'>[36]</a> <a href ="/abs/2406.13737" title="Abstract" id="2406.13737"> arXiv:2406.13737 </a> (replaced) [<a href="/pdf/2406.13737" title="Download PDF" id="pdf-2406.13737" aria-labelledby="pdf-2406.13737">pdf</a>, <a href="https://arxiv.org/html/2406.13737v3" title="View HTML" id="html-2406.13737" aria-labelledby="html-2406.13737" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2406.13737" title="Other formats" id="oth-2406.13737" aria-labelledby="oth-2406.13737">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> The Born regime of gravitational amplitudes </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Correia,+M">Miguel Correia</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Isabella,+G">Giulia Isabella</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 35 pages + appendices, 6 figures; v2: typos fixed, added references; v3: published version </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph) </div> <p class='mathjax'> We study the $2 \to 2$ scattering in the regime where the wavelength of the scattered objects is comparable to their distance but is much larger than any Compton wavelength in the quantum field theory. We observe that in this regime - which differs from the eikonal - the Feynman diagram expansion takes the form of a geometric series, akin to the Born series of quantum mechanics. Conversely, we can define the Feynman diagram expansion as the Born series of a relativistic effective-one-body (EOB) Schr枚dinger equation. For a gravitational theory in this regime we observe that the EOB Schr枚dinger equation reduces to the Regge-Wheeler or Teukolsky wave equations. We make use of this understanding to study the tree-level Compton scattering off a Kerr black hole. We compute the scalar and photon Compton amplitude up to $O(a^{30})$ in the black hole spin $a$ and propose an all-order expression. Remarkably, we find that boundary terms, which are typically neglected, give non-zero contact pieces necessary for restoring crossing symmetry and gauge invariance of the Kerr-Compton amplitude. </p> </div> </dd> <dt> <a name='item37'>[37]</a> <a href ="/abs/2408.13032" title="Abstract" id="2408.13032"> arXiv:2408.13032 </a> (replaced) [<a href="/pdf/2408.13032" title="Download PDF" id="pdf-2408.13032" aria-labelledby="pdf-2408.13032">pdf</a>, <a href="https://arxiv.org/html/2408.13032v2" title="View HTML" id="html-2408.13032" aria-labelledby="html-2408.13032" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2408.13032" title="Other formats" id="oth-2408.13032" aria-labelledby="oth-2408.13032">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Perturbations in $\mathbf{O}(D,D)$ string cosmology from double field theory </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Angus,+S">Stephen Angus</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Mukohyama,+S">Shinji Mukohyama</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> v2) Reference added; fixed typos. Version accepted for publication. v1) 41 + 16 pages (main body + title, appendices, and references) </div> <div class='list-journal-ref'><span class='descriptor'>Journal-ref:</span> Eur. Phys. J. C 85, no.2, 173 (2025) </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The low-energy limit of string theory contains additional gravitational degrees of freedom, a skew-symmetric tensor $B$-field and a scalar dilaton, that are not present in general relativity. Together with the metric, these three fields are naturally embedded in the $\mathbf{O}(D,D)$-symmetric framework of double field theory. The $\mathbf{O}(D,D)$ symmetry uniquely prescribes the interactions between the extended gravitational sector and other matter, leading to novel features beyond conventional string cosmology. In this work we present the equations of motion for linear perturbations around $\mathbf{O}(D,D)$ string cosmological backgrounds in $D=4$ under a scalar-vector-tensor decomposition. We obtain analytic solutions in the superhorizon limit for scalar perturbations around various homogeneous and isotropic background solutions, including some candidate models for bouncing cosmologies. The generalized energy-momentum tensor includes source terms for the $B$-field and dilaton, and we show how the resulting generalized conservation laws modify the conditions for conservation of curvature perturbations. </p> </div> </dd> <dt> <a name='item38'>[38]</a> <a href ="/abs/2408.15968" title="Abstract" id="2408.15968"> arXiv:2408.15968 </a> (replaced) [<a href="/pdf/2408.15968" title="Download PDF" id="pdf-2408.15968" aria-labelledby="pdf-2408.15968">pdf</a>, <a href="/format/2408.15968" title="Other formats" id="oth-2408.15968" aria-labelledby="oth-2408.15968">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> A nonlinear d'Alembert comparison theorem and causal differential calculus on metric measure spacetimes </div> <div class='list-authors'><a href="https://arxiv.org/search/math?searchtype=author&query=Beran,+T">Tobias Beran</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Braun,+M">Mathias Braun</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Calisti,+M">Matteo Calisti</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Gigli,+N">Nicola Gigli</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=McCann,+R+J">Robert J. McCann</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Ohanyan,+A">Argam Ohanyan</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=Rott,+F">Felix Rott</a>, <a href="https://arxiv.org/search/math?searchtype=author&query=S%C3%A4mann,+C">Clemens S盲mann</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 112 pages. Revised exposition, some proofs corrected, modified format. Comments welcome </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Differential Geometry (math.DG)</span>; General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); Metric Geometry (math.MG) </div> <p class='mathjax'> We introduce a variational first-order Sobolev calculus on metric measure spacetimes. The key object is the maximal weak subslope of an arbitrary causal function, which plays the role of the (Lorentzian) modulus of its differential. It is shown to satisfy certain chain and Leibniz rules, certify a locality property, and be compatible with its smooth analog. In this setup, we propose a quadraticity condition termed infinitesimal Minkowskianity, which singles out genuinely Lorentzian structures among Lorentz-Finsler spacetimes. Moreover, we establish a comparison theorem for a nonlinear yet elliptic $p$-d'Alembertian in a weak form under the timelike measure contraction property. As a particular case, this extends Eschenburg's classical estimate past the timelike cut locus. </p> </div> </dd> <dt> <a name='item39'>[39]</a> <a href ="/abs/2411.07939" title="Abstract" id="2411.07939"> arXiv:2411.07939 </a> (replaced) [<a href="/pdf/2411.07939" title="Download PDF" id="pdf-2411.07939" aria-labelledby="pdf-2411.07939">pdf</a>, <a href="https://arxiv.org/html/2411.07939v2" title="View HTML" id="html-2411.07939" aria-labelledby="html-2411.07939" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2411.07939" title="Other formats" id="oth-2411.07939" aria-labelledby="oth-2411.07939">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> One-loop $N$-point correlators in pure gravity </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Gomez,+H">Humberto Gomez</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Jusinskas,+R+L">Renann Lipinski Jusinskas</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Lopez-Arcos,+C">Cristhiam Lopez-Arcos</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Velez,+A+Q">Alexander Quintero Velez</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 8 pages. v2: minor improvements, matches published version </div> <div class='list-journal-ref'><span class='descriptor'>Journal-ref:</span> Phys. Rev. Lett. 134, 111602 (2025) </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> In this work we propose a simple algebraic recursion for the complete one-loop integrands of $N$-graviton correlators. This formula automatically yields the correct symmetry factors of individual diagrams, taking into account both the graviton and the ghost loop, and seamlessly controlling the related combinatorics. </p> </div> </dd> <dt> <a name='item40'>[40]</a> <a href ="/abs/2412.13256" title="Abstract" id="2412.13256"> arXiv:2412.13256 </a> (replaced) [<a href="/pdf/2412.13256" title="Download PDF" id="pdf-2412.13256" aria-labelledby="pdf-2412.13256">pdf</a>, <a href="https://arxiv.org/html/2412.13256v2" title="View HTML" id="html-2412.13256" aria-labelledby="html-2412.13256" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2412.13256" title="Other formats" id="oth-2412.13256" aria-labelledby="oth-2412.13256">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Generalized Clausius inequalities and entanglement production in holographic two-dimensional CFTs </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Kibe,+T">Tanay Kibe</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Mukhopadhyay,+A">Ayan Mukhopadhyay</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Roy,+P">Pratik Roy</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 51 pages, 8 figures, v2: version to appear in JHEP </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph) </div> <p class='mathjax'> Utilizing quantum information theory, it has been shown that irreversible entropy production is bounded from both below and above in physical processes. Both these bounds are positive and generalize the Clausius inequality. Such bounds are, however, obtained from distance measures in the space of states, which are hard to define and compute in quantum field theories. We show that the quantum null energy condition (QNEC) can be utilized to obtain both lower and upper bounds on irreversible entropy production for quenches leading to transitions between thermal states carrying uniform momentum density in two dimensional holographic conformal field theories. We achieve this by refining earlier methods and developing an algebraic procedure for determining HRT surfaces in arbitrary Ba帽ados-Vaidya geometries which are dual to quenches involving transitions between general quantum equilibrium states (e.g. thermal states) where the QNEC is saturated. We also discuss results for the growth and thermalization of entanglement entropy for arbitrary initial and final temperatures and momentum densities. The rate of quadratic growth of entanglement just after the quench depends only on the change in the energy density and is independent of the entangling length. For sufficiently large entangling lengths, the entanglement tsunami phenomenon can be established. Finally, we study recovery of the initial state from the evolving entanglement entropy and argue that the Renyi entropies should give us a refined understanding of scrambling of quantum information. </p> </div> </dd> <dt> <a name='item41'>[41]</a> <a href ="/abs/2412.14036" title="Abstract" id="2412.14036"> arXiv:2412.14036 </a> (replaced) [<a href="/pdf/2412.14036" title="Download PDF" id="pdf-2412.14036" aria-labelledby="pdf-2412.14036">pdf</a>, <a href="https://arxiv.org/html/2412.14036v3" title="View HTML" id="html-2412.14036" aria-labelledby="html-2412.14036" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2412.14036" title="Other formats" id="oth-2412.14036" aria-labelledby="oth-2412.14036">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Combinatorial interpretation of the coefficients of the causal set d'Alembertian </div> <div class='list-authors'><a href="https://arxiv.org/search/math?searchtype=author&query=Yeats,+K">Karen Yeats</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 16 pages, typos corrected in corollaries and extra references at editor's request </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">Combinatorics (math.CO)</span>; General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph) </div> <p class='mathjax'> The causal set theory d'Alembertian has rational coefficients for which alternating expressions are known. Here, a combinatorial interpretation of these numbers is given. </p> </div> </dd> <dt> <a name='item42'>[42]</a> <a href ="/abs/2501.09886" title="Abstract" id="2501.09886"> arXiv:2501.09886 </a> (replaced) [<a href="/pdf/2501.09886" title="Download PDF" id="pdf-2501.09886" aria-labelledby="pdf-2501.09886">pdf</a>, <a href="https://arxiv.org/html/2501.09886v2" title="View HTML" id="html-2501.09886" aria-labelledby="html-2501.09886" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2501.09886" title="Other formats" id="oth-2501.09886" aria-labelledby="oth-2501.09886">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Holographic Bound of Casimir Effect in General Dimensions </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Miao,+R">Rong-Xin Miao</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 27 pages, 8 figures, accepted for publication in JHEP </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> Recently, it has been proposed that holography imposes a universal lower bound on the Casimir effect for 3d BCFTs. This paper generalizes the discussions to higher dimensions. We find Einstein gravity, DGP gravity, and Gauss-Bonnet gravity sets a universal lower bound of the strip Casimir effect in general dimensions. We verify the holographic bound by free theories and $O(N)$ models in the $\epsilon$ expansions. We also derive the holographic bound of the Casimir effect for a wedge and confirm free theories obey it. It implies holography sets a lower bound of the Casimir effect for general boundary shapes, not limited to the strip. Finally, we briefly comment on the impact of mass and various generalizations and applications of our results. </p> </div> </dd> <dt> <a name='item43'>[43]</a> <a href ="/abs/2502.12290" title="Abstract" id="2502.12290"> arXiv:2502.12290 </a> (replaced) [<a href="/pdf/2502.12290" title="Download PDF" id="pdf-2502.12290" aria-labelledby="pdf-2502.12290">pdf</a>, <a href="https://arxiv.org/html/2502.12290v2" title="View HTML" id="html-2502.12290" aria-labelledby="html-2502.12290" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2502.12290" title="Other formats" id="oth-2502.12290" aria-labelledby="oth-2502.12290">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Asymptotic safety, quantum gravity, and the swampland: a conceptual assessment </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Basile,+I">Ivano Basile</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Knorr,+B">Benjamin Knorr</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Platania,+A">Alessia Platania</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Schiffer,+M">Marc Schiffer</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 48 pages, V2: references added </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> We provide a conceptual assessment of some aspects of fundamental quantum field theories of gravity in light of foundational aspects of the swampland program. On the one hand, asymptotically safe quantum gravity may provide a simple and predictive framework, thanks to a finite number of relevant parameters. On the other hand, a (sub-)set of intertwined swampland conjectures on the consistency of quantum gravity can be argued to be universal via effective field theory considerations. We answer whether some foundational features of these frameworks are compatible. This involves revisiting and refining several arguments (and loopholes) concerning the relation between field-theoretic descriptions of gravity and general swampland ideas. We identify the thermodynamics of black holes, spacetime topology change, and holography as the core aspects of this relation. We draw lessons on the features that a field theoretic description of gravity must (not) have to be consistent with fundamental principles underlying the swampland program, and on the universality of the latter. </p> </div> </dd> <dt> <a name='item44'>[44]</a> <a href ="/abs/2502.17179" title="Abstract" id="2502.17179"> arXiv:2502.17179 </a> (replaced) [<a href="/pdf/2502.17179" title="Download PDF" id="pdf-2502.17179" aria-labelledby="pdf-2502.17179">pdf</a>, <a href="https://arxiv.org/html/2502.17179v2" title="View HTML" id="html-2502.17179" aria-labelledby="html-2502.17179" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2502.17179" title="Other formats" id="oth-2502.17179" aria-labelledby="oth-2502.17179">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Late-Time Saturation of Black Hole Complexity </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Gautason,+F+F">Fri冒rik Freyr Gautason</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Mohan,+V">Vyshnav Mohan</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Thorlacius,+L">L谩rus Thorlacius</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 35 pages and 9 figures. v2: typos fixed and references added </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The holographic complexity of a static spherically symmetric black hole, defined as the volume of an extremal surface, grows linearly with time at late times in general relativity. The growth comes from a region at a constant transverse area inside the black hole and continues forever in the classical theory. In this region the volume complexity of any spherically symmetric black hole in $d+1$ spacetime dimensions reduces to a geodesic length in an effective two-dimensional JT-gravity theory. The length in JT-gravity has been argued to saturate at very late times via non-perturbative corrections obtained from a random matrix description of the gravity theory. The same argument, applied to our effective JT-gravity description of the volume complexity, leads to complexity saturation at times of exponential order in the Bekenstein-Hawking entropy of a $d+1$-dimensional black hole. Along the way, we explore a simple toy model for complexity growth, based on a discretisation of Nielsen complexity geometry, that can be analytically shown to exhibit the expected late-time complexity saturation. </p> </div> </dd> <dt> <a name='item45'>[45]</a> <a href ="/abs/2502.20881" title="Abstract" id="2502.20881"> arXiv:2502.20881 </a> (replaced) [<a href="/pdf/2502.20881" title="Download PDF" id="pdf-2502.20881" aria-labelledby="pdf-2502.20881">pdf</a>, <a href="https://arxiv.org/html/2502.20881v2" title="View HTML" id="html-2502.20881" aria-labelledby="html-2502.20881" rel="noopener noreferrer" target="_blank">html</a>, <a href="/format/2502.20881" title="Other formats" id="oth-2502.20881" aria-labelledby="oth-2502.20881">other</a>] </dt> <dd> <div class='meta'> <div class='list-title mathjax'><span class='descriptor'>Title:</span> Hamiltonian Neural Networks approach to fuzzball geodesics </div> <div class='list-authors'><a href="https://arxiv.org/search/hep-th?searchtype=author&query=Cipriani,+A">Andrea Cipriani</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=De+Santis,+A">Alessandro De Santis</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Di+Russo,+G">Giorgio Di Russo</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Grillo,+A">Alfredo Grillo</a>, <a href="https://arxiv.org/search/hep-th?searchtype=author&query=Tabarroni,+L">Luca Tabarroni</a></div> <div class='list-comments mathjax'><span class='descriptor'>Comments:</span> 25 pages + Appendices, 39 figures </div> <div class='list-subjects'><span class='descriptor'>Subjects:</span> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span>; Machine Learning (cs.LG); General Relativity and Quantum Cosmology (gr-qc) </div> <p class='mathjax'> The recent increase in computational resources and data availability has led to a significant rise in the use of Machine Learning (ML) techniques for data analysis in physics. However, the application of ML methods to solve differential equations capable of describing even complex physical systems is not yet fully widespread in theoretical high-energy physics. Hamiltonian Neural Networks (HNNs) are tools that minimize a loss function defined to solve Hamilton equations of motion. In this work, we implement several HNNs trained to solve, with high accuracy, the Hamilton equations for a massless probe moving inside a smooth and horizonless geometry known as D1-D5 circular fuzzball. We study both planar (equatorial) and non-planar geodesics in different regimes according to the impact parameter, some of which are unstable. Our findings suggest that HNNs could eventually replace standard numerical integrators, as they are equally accurate but more reliable in critical situations. </p> </div> </dd> </dl> <div class='paging'>Total of 45 entries </div> <div class='morefewer'>Showing up to 2000 entries per page: <a href=/list/gr-qc/new?skip=0&show=1000 rel="nofollow"> fewer</a> | <span style="color: #454545">more</span> | <span style="color: #454545">all</span> </div> </div> </div> </div> </main> <footer style="clear: both;"> <div class="columns is-desktop" role="navigation" aria-label="Secondary" style="margin: -0.75em -0.75em 0.75em -0.75em">  <div class="column" style="padding: 0;"> <div class="columns"> <div class="column"> <ul style="list-style: none; line-height: 2;"> <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 style="list-style: none; line-height: 2;"> <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" style="padding: 0;"> <div class="columns"> <div class="column"> <ul style="list-style: none; 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