Wed·Feb 26, 2025Wednesday·February 26, 2025

1. 01*

   Listening for ultra-heavy dark matter with underwater acoustic detectors

   Damon Cleaver🇬🇧 · Christopher McCabe🇬🇧 · Ciaran A. J. O'Hare

   Ultra-heavy dark matter candidates evade traditional direct detection experiments due to their low particle flux. We explore the potential of large underwater acoustic arrays, originally developed for ultra-high energy neutrino detection, to detect ultra-heavy dark matter interactions. These particles deposit energy via nuclear scattering while traversing seawater, generating thermo-acoustic waves detectable by hydrophones. We present the first robust first-principles calculation of dark matter-induced acoustic waves, establishing a theoretical framework for signal modelling and sensitivity estimates. Our framework incorporates frequency-dependent attenuation effects, including viscous and chemical relaxation, not considered in previous calculations. A sensitivity analysis for a hypothetical 100 cubic kilometre hydrophone array in the Mediterranean Sea demonstrates that such an array could extend sensitivity to the previously unexplored mass range of $0.1$-$10\mu \mathrm{g}$ ($\sim 10^{20}$-$10^{23}\mathrm{GeV}$), with sensitivity to both spin-independent and spin-dependent interactions. Our results establish acoustic detection as a complementary dark matter search method, enabling searches in existing hydrophone data and informing future detector designs.

   hep-phastro-ph.COhep-exPRD(2025)·4 citations
2. 02*

   Unraveling particle dark matter with Physics-Informed Neural Networks

   M.P. Bento🇵🇹 · H.B. Câmara🇵🇹 · J.F. Seabra🇵🇹

   We parametrically solve the Boltzmann equations governing freeze-in dark matter (DM) in alternative cosmologies with Physics-Informed Neural Networks (PINNs), a mesh-free method. Through inverse PINNs, using a single DM experimental point -- observed relic density -- we determine the physical attributes of the theory, namely power-law cosmologies, inspired by braneworld scenarios, and particle interaction cross sections. The expansion of the Universe in such alternative cosmologies has been parameterized through a switch-like function reproducing the Hubble law at later times. Without loss of generality, we model more realistically this transition with a smooth function. We predict a distinct pair-wise relationship between power-law exponent and particle interactions: for a given cosmology with negative (positive) exponent, smaller (larger) cross sections are required to reproduce the data. Lastly, via Bayesian methods, we quantify the epistemic uncertainty of theoretical parameters found in inverse problems.

   hep-phcs.LGPLB(2025)·9 citations
3. 03*

   Resummation for $s$-channel single-top production

   Nikolaos Kidonakis🇺🇸

   I present higher-order results for $s$-channel single-top-quark production that are derived from soft-gluon resummation. I show that the soft-gluon corrections provide the dominant contribution to the QCD corrections, and that they approximate very well the exact results through NNLO. Furthermore, approximate N${}^3$LO corrections are computed by using the expansion of the resummed cross section to third order in the strong coupling. The calculation treats the final-state $b$-quarks as massless but I also show how to extend the formalism to the case of massive $b$-quarks. The higher-order corrections are large at LHC energies and they improve the theoretical accuracy.

   hep-phNPB(2026)·6 citations
4. 04*

   Exclusive $J/\psi$ production in proton-proton collisions adopting GPD approach

   Ya-Ping Xie🇨🇳 · S.V.Goloskokov🇷🇺

   Exclusive $J/\psi$ production is investigated in proton-proton collisions employing GPD approach with GK model. Three sets gluon density are used to calculate exclusive $J/\psi$ production. The survival factors and equivalent photon approximation are applied to predict the exclusive $J/\psi$ photoproduction in proton-proton collisions. The GPD method prediction gives a good agreement with the experimental data at LHCb. The exclusive $J/\psi$ production is given in proton-proton collisions at RHIC and NICA. These predictions of GPD approach can be employed to estimate the exclusive $J/\psi$ cross sections in future proton-proton collisions.

   hep-phEPJC(2025)·4 citations
5. 05*

   Fragmentation Functions of Charged Hadrons at Next-to-Next-to-Leading Order and Constraints on the Proton Parton Distribution Functions

   Jun Gao🇨🇳 · XiaoMin Shen🇨🇳 · Hongxi Xing🇨🇳 · Yuxiang Zhao🇨🇳 · Bin Zhou🇨🇳

   We present the first global analysis of fragmentation functions (FFs) for light charged hadrons (${\pi }^{\pm }$, $K^{\pm }$) at full next-to-next-to-leading order in Quantum Chromodynamics (QCD), incorporating world data from both single-inclusive electron-positron annihilation and semi-inclusive deep-inelastic scattering. The collinear factorization has been tested with low-momentum-transfer data and has demonstrated success at high hadron momenta. Additionally, we study the impact of current global data on hadron production to the parton distribution functions (PDFs), and find they favor a reduced asymmetry in the strange (anti-) quark PDFs, as compared to the asymmetry predicted by state-of-the-art PDFs derived from inclusive data.

   hep-phhep-exPRL(2025)·25 citations
6. 06*

   Five-body systems with Bethe-Salpeter equations

   Gernot Eichmann🇦🇹 · M.T. Peña🇵🇹 · Raul D. Torres🇵🇹

   We extend the Bethe-Salpeter formalism to systems made of five valence particles. Restricting ourselves to two-body interactions, we derive the subtraction terms necessary to prevent overcounting. We solve the five-body Bethe-Salpeter equation numerically for a system of five scalar particles interacting by a scalar exchange boson. To make the calculations tractable, we implement properties of the permutation group S5 and construct an approximation based on intermediate two- and three-body poles. We extract the five-body ground and excited states along with the spectra obtained from the two-, three-, and four-body equations. In the limit of a massless exchange particle, the two-, three, four- and five-body states coexist within a certain range of the coupling strength, whereas for heavier exchange particles the five-body system becomes Borromean. Our study serves as a building block for the calculation of pentaquark properties using functional methods.

   hep-phnucl-thPLB(2025)·8 citations
7. 07*

   Constraints on asymmetric production of long-lived scalars at the Large Hadron Collider

   Thomas Chehab🇫🇷 · Louie Dartmoor Corpe🇫🇷 · Andreas Goudelis🇫🇷 · Abdelhamid Haddad🇫🇷 · Louise Millot🇫🇷

   Searches for pair-produced long-lived particles (LLPs) at the LHC commonly operate under the assumption that the two LLPs are identical. In this paper we entertain the possibility that the targeted final states are, instead, induced by a LLP pair with different masses and/or lifetimes. We propose a simple and intuitively-parametrised toy model in order to study such asymmetric production of LLPs. Using the recasting material of a recent search for displaced jets by the ATLAS collaboration, we demonstrate that we can set constraints on the production cross-section times branching fraction into jets for a variety of asymmetric LLP and mediator mass combinations.

   hep-phEPJC(2025)·0 citations
8. 08*

   Unified neutrino mixing and approximate $\mu$-$\tau$ reflection symmetry

   Yuta Hyodo🇯🇵 · Teruyuki Kitabayashi🇯🇵

   We investigate the phenomenology of a unified neutrino mixing framework, which serves as the origin of well-known neutrino mixing schemes such as the tribimaximal mixing (TBM), bimaximal mixing (BM), golden ratio mixing (GRM) and hexagonal mixing (HM). Our analysis reveals that the predicted sum of neutrino masses derived from an approximate $\mu$-$\tau$ reflection symmetric flavor neutrino mass matrix based on the unified neutrino mixing with an inverted mass ordering, is excluded from DESI2024 and Supernova Ia luminosity distance data. This conclusion implies that TBM, BM, GRM, and HM, under an approximate $\mu$-$\tau$ reflection symmetry with an inverted mass ordering of neutrinos, are also excluded from observations.

   hep-phMod.Phys.Lett.A(2025)·5 citations
9. 09*

   Quantum Wishlist: Lessons from Parton Showers

   Masahito Yamazaki🇯🇵

   We discuss general criteria that could guide us in applying quantum algorithms/computers to problems in high-energy physics. We then discuss the particular example of parton showers with quantum interference. We summarize the basic ideas behind the classical and quantum parton shower Monte Carlo algorithms and highlight the importance of quantum/classical hybrid algorithms. Our finding in quantum parton showers could serve as a useful case study for further exploration of quantum algorithms/computers in high-energy physics.

   hep-phhep-thquant-phPoS(2025)·1 citation
10. 10*

    Lepton flavor violating decays $l_j\to l_i\gamma$, $l_j\to 3l_i$ and $\mu \to e+q\bar{q}$ in the N-B-LSSM

    Rong-Zhi Sun🇨🇳 · Shu-Min Zhao🇨🇳 · Ming-Yue Liu🇨🇳 · Xing-Yu Han🇨🇳 · Song Gao🇨🇳 · Xing-Xing Dong🇨🇳

    The N-B-LSSM is an extension of the minimal supersymmetric standard model (MSSM) with the addition of three singlet new Higgs superfields and right-handed neutrinos, whose local gauge group is $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y\times U(1{)}_{B-L}$. In the N-B-LSSM, we study lepton flavor violating decays $l_j\to l_i\gamma$, $l_j\to 3l_i$ and $\mu \to e+q\bar{q}$ $(j=\tau ,\mu ,i=\mu ,e$ and $i\ne j)$. Based on the current experimental limitations, we carry out detailed parameter scanning and numerical calculations to analyse the effects of different sensitive parameters on lepton flavor violation (LFV) in the N-B-LSSM. The numerical results show that the non-diagonal elements involving the initial and final leptons are main sensitive parameters and LFV sources. This work can provide a strong basis for exploring new physics (NP) beyond the Standard Model (SM).

    hep-phEPJC(2025)·2 citations
11. 11*

    Muon-Decay Parameters from COHERENT

    Víctor Bresó-Pla🇩🇪 · Sergio Cruz-Alzaga🇪🇸 · Martín González-Alonso🇪🇸 · Suraj Prakash🇪🇸

    We demonstrate that measurements of Coherent Elastic Neutrino-Nucleus Scattering (CE$\nu$NS) at spallation sources are valuable probes of muon-decay physics. Using COHERENT data we derive the first direct constraint on the Michel parameters governing the ${\bar{\nu }}_{\mu }$ energy distribution. We also discuss future sensitivities, the implications for the Lorentz structure of the interactions mediating muon decay and the application to other neutrino-production mechanisms like pion decay.

    hep-phPRL(2025)·5 citations
12. 12*

    Constraints on Lorentz-invariance violation in the neutrino sector from the ultrahigh-energy event KM3-230213A

    Yu-Ming Yang🇨🇳 · Xing-Jian Lv🇨🇳 · Xiao-Jun Bi🇨🇳 · Peng-Fei Yin🇨🇳

    Lorentz invariance is a fundamental symmetry of spacetime and serves as the cornerstone of modern physics, supporting the constancy of the speed of light. A crucial implication of this principle is that no particle can propagate faster than this universal speed limit. In this study, we present a stringent neutrino-based test of Lorentz invariance, utilizing the highest-energy neutrino ever detected, known as event KM3-230213A. The detection of this neutrino, with measured energy of approximately 220 PeV, allows us to establish a lower bound on the scale of second-order Lorentz invariance violation, quantified as \(\Lambda_2>5.0\times 10^{19}\) GeV at 90 \% confidence level.

    hep-phastro-ph.HEPRD(2025)·19 citations
13. 13*

    Exploring sub-GeV dark matter via $s$-wave, $p$-wave, and resonance annihilation with CMB data

    Yu-Ning Wang🇨🇳 · Xin-Chen Duan🇨🇳 · Tian-Peng Tang🇨🇳 · Ziwei Wang🇨🇳 · Yue-Lin Sming Tsai🇨🇳

    We revisit constraints on sub-GeV dark matter (DM) annihilation via $s$-wave, $p$-wave, and resonance processes using current and future CMB data from Planck, FIRAS, and upcoming experiments such as LiteBIRD, CMB-S4, PRISTINE, and PIXIE. For $s$-wave annihilation, we provide updated limits for both $e^{+}{e}^{-}$ and $\pi \pi$ channels, with the profile likelihood method yielding stronger constraints than the marginal posterior method. In the $p$-wave case, we comprehensively present a model-independent inequality for the $95\%$ upper limits from FIRAS, PRISTINE, and PIXIE, with future experiments expected to surpass current BBN limits. For resonance annihilation, we report -- for the first time -- the $95\%$ upper limits on the decay branching ratio of the mediator particle, when the resonance peaks during the recombination epoch. Overall, our study highlights the complementary strengths of $\mu$-distortion and CMB anisotropies in probing sub-GeV DM annihilation.

    hep-phastro-ph.COJCAP(2025)·14 citations
14. 14*

    On the momentum space structure of the quark propagator

    O. Oliveira🇵🇹 · T. Frederico🇧🇷 · W. de Paula🇧🇷

    The structure of the quark propagator in momentum space is explored taking into account non-perturbative QCD dynamics constraints for the quark spectral densities derived previously. We assume that the scalar and vector component of the quark propagator share a simple pole but not its residuum, together with other structures. Furthermore, a connection between the poles of the quark propagator and the zeros of the quark wave function $Z(p^2)$ is established. Asymptotic scaling laws for the representation of the quark propagator, after removing the shared pole, are also derived. The confrontation of our results with lattice data for the full QCD quark propagator data are in good agreement. Exploring the link with the lattice data and looking at the Bethe-Salpeter vertex and amplitude, in the chiral limit, we are able to provide estimations for these quantities, for $f_{\pi }$ and for the shared pole mass. The pole mass reproduces the constituent quark mass used in the quark models.

    hep-phhep-thnucl-thEPJC(2025)·3 citations
15. 15*

    Rotational stability of magnetic field in rotating quark-gluon plasma

    Aritra Das🇺🇸 · Kirill Tuchin🇺🇸

    Relaxation of the magnetic field in rigidly rotating quark-gluon plasma is studied. It is shown that the infrared modes satisfying $k<|m|\Omega$ and $k<|m\pm 1|\Omega$, where integer $m$ is the projection of the orbital angular momentum along the rotating axis and $\Omega$ is the angular velocity, are unstable. The instability onset time and the magnetic field growth rate are computed for a standard initial profile of the magnetic field. Given the present phenomenological values of $\Omega$ and electrical conductivity $\sigma$ the instability is not expected to be a significant factor in the field's time evolution.

    hep-phnucl-thNPA(2025)·6 citations
16. 16*

    Pion Decay

    Douglas Bryman🇨🇦 · Robert Shrock🇺🇸

    The decays of pions, the lightest particles composed of quarks, provide important insight into fundamental questions in particle physics including basic symmetries, the universality of fermionic weak interactions, and aspects of the strong interaction described by Quantum Chromodynamics (QCD). An introduction to the theoretical and experimental study of charged and neutral pion decays is presented.

    hep-phhep-ex6 citations
17. 17*

    The $D_{s1}(2460)\to D_s{\pi }^{+}{\pi }^{-}$ decay from a $D_{s1}$ molecular perspective

    L. Roca🇪🇸 · J.M.Dias🇧🇷 · E. Oset🇨🇳

    We conduct a theoretical study of the $D_{s1}(2460)\to D_s{\pi }^{+}{\pi }^{-}$ decay from the perspective that the $D_{s1}$ is a molecular state, built mostly from the $D^{\ast }K$ and $D_s^{\ast }\eta$ components. The $D^{\ast }$ and $D_s^{\ast }$ mesons are allowed to decay into two pseudoscalars, with one of them merging with the other pseudoscalar that forms the $D_{s1}$ state, ultimately leading to the ${\pi }^{+}{\pi }^{-}{D}_s$ final state. This results in a triangle diagram mechanism where all theoretical ingredients are well-known, leading to a free parameter framework. We evaluate the mass distributions of particle pairs and find good agreement with the experimental distributions of a recent LHCb experiment, providing strong support to the molecular picture of the $D_{s1}(2460)$ state. We also discuss the role played by the scalar mesons $f_0(500)$ and $f_0(980)$, at odds with the interpretation of the experimental analysis.

    hep-phEPJC(2025)·8 citations
18. 18*

    Towards a Manifestly Causal Approach to Particle Scattering

    Robert Dickinson🇬🇧 · Jeff Forshaw🇬🇧 · Ross Jenkinson🇬🇧 · Peter Millington🇬🇧

    We introduce a new, probability-level approach to calculations in scalar field particle scattering. The approach involves the implicit summation over final states, which makes causality manifest since retarded propagators emerge naturally. Novel diagrams represent algebraic terms at the probability level, akin to Feynman diagrams at the amplitude level. We conjecture a list of rules that generate all probability-level diagrams for particle scattering processes in which one is fully inclusive over final states that contain no initial-state particles. These rules are confirmed using some fixed-order examples. The inclusivity and causal structure of this formalism may offer insights into the cancellation of infrared divergences if applied to gauge theory calculations.

    hep-phhep-thPRD(2025)·3 citations
19. 19*

    On the Simulation of Hidden Parton Showers in the Conformal Window

    Suchita Kulkarni🇦🇹 · Joshua Lockyer🇦🇹 · Matthew J. Strassler🇺🇸

    We consider confining Hidden Valley/Dark Sector theories containing many dark quark flavors. These theories are in the ``conformal window'': they reach an infrared fixed point when their quarks are massless, and have unfamiliar confinement when the quark masses are non-zero but small. Their jets of hidden hadrons may be quite different from those familiar from QCD, but their details cannot currently be simulated even qualitatively. This is partly due to the use of approximations to the two-loop running coupling in existing event generators' parton showers, which are not broadly applicable across the conformal window. We argue that the exact two-loop running coupling, and a corresponding Sudakov factor employing that coupling, must be implemented in simulation packages in order to allow phenomenological studies of these theories.

    hep-phhep-exJHEP(2025)·7 citations
20. 20*

    Renormalization group analysis of electromagnetic properties of the deuteron

    Thomas R. Richardson🇺🇸 · Immo C. Reis🇩🇪

    The role of radiative corrections in low energy nuclear physics is beginning to receive more scrutiny. We examine the impact of these corrections for the deuteron charge form factor and the radiative capture process $np\to d\gamma$ through the velocity renormalization group. In both cases, we find percent level shifts in the relevant observables after evolving the subtraction velocity to the typical velocity of nucleons in the bound state. This suggests that electromagnetic corrections constitute a non-negligible source of uncertainty in existing few-body calculations.

    ↳ nucl-thhep-phPRC(2025)·3 citations
21. 21*

    Dynamical evolution of critical fluctuations with second-order baryon diffusion coupled to chiral condensate

    Azumi Sakai🇯🇵 · Koichi Murase🇯🇵 · Hirotsugu Fujii🇯🇵 · Tetsufumi Hirano🇯🇵

    We develop a dynamical model to describe critical fluctuations in heavy-ion collisions, incorporating the baryon diffusion current and chiral condensate as dynamical degrees of freedom, to address their nontrivial scale separation. The model couples fluctuations of the chiral condensate $\sigma$ with baryon density fluctuations $n$ and the diffusion current $\nu$ based on a second-order diffusion equation with a finite relaxation time of the baryon diffusion ${\tau }_{\mathrm{R}}$. We analyze the spacetime evolution and these correlation functions of the fluctuations in one-dimensionally expanding background. We confirm that an appropriate relaxation time ${\tau }_{\mathrm{R}}$ ensures causality. We show that propagating waves with finite ${\tau }_{\mathrm{R}}$ split into two modes at the critical temperature due to a rapid change of kinetic coefficients. In the correlation functions, we find that dynamical $\sigma$ blurs the structure and peak around the critical temperature. With finite ${\tau }_{\mathrm{R}}$, the effect of the critical fluctuations persists longer into the later stages of the evolution. These findings suggest importance of dynamical effects of the chiral condensate and baryon diffusion current in identifying critical-point signals in heavy-ion collisions, where the scale separation is nontrivial.

    ↳ nucl-thhep-phPRC(2025)·1 citation
22. 22*

    Rapidly spinning dark matter-admixed neutron stars

    Lorenzo Cipriani🇮🇹 · Edoardo Giangrandi🇵🇹 · Violetta Sagun🇬🇧 · Daniela D. Doneva🇩🇪 · Stoytcho S. Yazadjiev🇧🇬

    Millisecond pulsars, representing the older neutron star population, are believed to have undergone a prolonged period of dark matter accumulation, resulting in a higher dark matter content. Their extreme rotation makes them unique laboratories for studying rapidly rotating neutron stars admixed with dark matter. In this work, we model uniformly rotating neutron stars with a dark matter component that rotates independently from the baryon matter, allowing for the investigation of both co-rotating and counter-rotating scenarios. We examine the impact of dark matter rotation on the macroscopic properties of neutron stars, including the mass-radius relation, the mass-shedding Keplerian limit, and moments of inertia, for various dark matter particle masses and total fractions, considering both core and halo distributions. Our findings provide a more comprehensive understanding of how dark matter influences the equilibrium properties of rotating neutron stars, offering new insights into the astrophysical implications of self-interacting dark matter.

    ↳ astro-ph.HEgr-qchep-phnucl-thPRD(2025)·16 citations
23. 23*

    Two- and three-meson scattering amplitudes with physical quark masses from lattice QCD

    Sebastian M. Dawid🇺🇸 · Zachary T. Draper🇺🇸 · Andrew D. Hanlon🇺🇸 · Ben Hörz🇩🇪 · Colin Morningstar🇺🇸 · Fernando Romero-López🇨🇭 · Stephen R. Sharpe🇺🇸 · Sarah Skinner🇺🇸

    We study systems of two and three mesons composed of pions and kaons at maximal isospin using four CLS ensembles with $a\approx 0.063$fm, including one with approximately physical quark masses. Using the stochastic Laplacian-Heaviside method, we determine the energy spectrum of these systems including many levels in different momentum frames and irreducible representations. Using the relativistic two- and three-body finite-volume formalism, we constrain the two and three-meson K matrices, including not only the leading $s$ wave, but also $p$ and $d$ waves. By solving the three-body integral equations, we determine, for the first time, the physical-point scattering amplitudes for $3{\pi }^{+}$, $3K^{+}$, ${\pi }^{+}{\pi }^{+}{K}^{+}$ and $K^{+}{K}^{+}{\pi }^{+}$ systems. These are determined for total angular momentum $J^P=0^{-}$, $1^{+}$, and $2^{-}$. We also obtain accurate results for $2{\pi }^{+}$, ${\pi }^{+}{K}^{+}$, and $2K^{+}$ phase shifts. We compare our results to Chiral Perturbation Theory, and to phenomenological fits.

    ↳ hep-lathep-phnucl-thPRD(2025)·29 citations
24. 24*

    A Perspective on Symbolic Machine Learning in Physical Sciences

    Nour Makke🇮🇹 · Sanjay Chawla🇶🇦

    Machine learning is rapidly making its pathway across all of the natural sciences, including physical sciences. The rate at which ML is impacting non-scientific disciplines is incomparable to that in the physical sciences. This is partly due to the uninterpretable nature of deep neural networks. Symbolic machine learning stands as an equal and complementary partner to numerical machine learning in speeding up scientific discovery in physics. This perspective discusses the main differences between the ML and scientific approaches. It stresses the need to develop and apply symbolic machine learning to physics problems equally, in parallel to numerical machine learning, because of the dual nature of physics research.

    ↳ cs.LGhep-phhep-th3 citations
25. 25*

    WIMP Dark Matter Search using a 3.1 Tonne-Year Exposure of the XENONnT Experiment

    E. Aprile🇺🇸 · J. Aalbers🇳🇱 · K. Abe🇯🇵 · S. Ahmed Maouloud🇫🇷 · L. Althueser🇩🇪 · B. Andrieu🇫🇷 · E. Angelino🇮🇹 · D. Antón Martin🇺🇸 · S. R. Armbruster🇩🇪 · F. Arneodo🇦🇪 · L. Baudis🇨🇭 · M. Bazyk🇫🇷 and 166 other authors

    We report on a search for weakly interacting massive particle (WIMP) dark matter (DM) via elastic DM-xenon-nucleus interactions in the XENONnT experiment. We combine datasets from the first and second science campaigns resulting in a total exposure of 3.1 tonne-years. In a blind analysis of nuclear recoil events with energies above $3.8\mathrm{ke}{\mathrm{V}}_{\mathrm{NR}}$, we find no significant excess above background. We set new upper limits on the spin-independent WIMP-nucleon scattering cross section for WIMP masses above $10\mathrm{GeV}/c^2$ with a minimum of $1.7\times 10^{-47}\mathrm{c}{\mathrm{m}}^2$ at $90\%$ confidence level for a WIMP mass of $30\mathrm{GeV}/c^2$. We achieve a best median sensitivity of $1.4\times 10^{-47}\mathrm{c}{\mathrm{m}}^2$ for a $41\mathrm{GeV}/c^2$ WIMP. Compared to the result from the first XENONnT science dataset, we improve our sensitivity by a factor of up to 1.8.

    ↳ hep-exastro-ph.COastro-ph.IMhep-ph+1PRL(2025)·179 citations
26. 26*

    Bispectrum at NLO in single field inflation: conservation and squeezed limit

    Ignatios Antoniadis🇹🇭 · Auttakit Chatrabhuti🇹🇭 · Jules Cunat🇫🇷 · Hiroshi Isono🇹🇭

    In a recent paper, we computed the bispectrum of primordial density perturbations in CMB to second order in the slow-roll parameters of single field inflation, and found logarithmic infrared contributions that diverge in both large physical distances and squeezed limit where one momentum vanishes. In this work, we provide an independent test of the result by checking its conservation and the validity of the consistency relation between the squeezed limit of the bispectrum and the square of the power spectrum. Despite the violation of the main assumption for its general proofs which is the finiteness of the relevant observables in these limits, we find that the identity continues to hold in the vicinity of the squeezed limit and large time.

    ↳ hep-thastro-ph.COgr-qchep-phEPJC(2025)·2 citations
27. 27*

    Primordial black holes as cosmic expansion accelerators

    Konstantinos Dialektopoulos🇷🇴 · Theodoros Papanikolaou🇮🇹 · Vasilios Zarikas🇬🇷

    We propose a novel and natural mechanism for cosmic acceleration driven by primordial black holes (PBHs) exhibiting repulsive behavior. Using a new ``Swiss Cheese'' cosmological approach, we demonstrate that this cosmic acceleration mechanism is a general phenomenon by examining three regular black hole spacetimes - namely the Hayward, the Bardeen and the Dymnikova spacetimes - as well as the singular de Sitter-Schwarzschild spacetime. Interestingly, by matching these black hole spacetimes with an isotropic and homogeneous expanding Universe, we obtain a phase of cosmic acceleration that ends at an energy scale characteristic to the black hole parameters or due to black hole evaporation. This cosmic acceleration mechanism can be relevant either to an inflationary phase with a graceful exit and reheating or to an early dark energy type of contribution pertinent to the Hubble tension. Remarkably, we find that ultra-light PBHs with masses $m<5\times 10^8\mathrm{g}$ dominating the energy content of the Univese before Big Bang Nucleosynthesis, can drive a successful inflationary expansion era without the use of an inflaton field. Additionally, PBHs with masses $m\sim 10^{12}\mathrm{g}$ and abundances $0.107<{\Omega }_{\mathrm{PBH}}^{\mathrm{eq}}<0.5$, slightly before matter-radiation equality, can produce a substantial amount of early dark energy, helping to alleviate the $H_0$ tension.

    ↳ gr-qcastro-ph.COhep-phPLB(2025)·26 citations
28. 28*

    Reconstructing early universe evolution with gravitational waves from supercooled phase transitions

    Adam Gonstal🇵🇱 · Marek Lewicki🇵🇱 · Bogumila Swiezewska🇵🇱

    We study gravitational waves from supercooled cosmological first-order phase transitions. If such a transition is followed by inefficient reheating, the evolution history of the universe is modified by a period of early matter domination. This leaves an imprint on the predicted gravitational-wave spectra. Using Fisher analysis we show the parameter space in reach of upcoming gravitational wave observatories where reheating can be probed due to its impact on the stochastic background produced by the transition. We use both the simplified geometric parametrisation and the thermodynamical one explicitly including the decay rate of the field undergoing the transition as a parameter determining the spectrum. We show the expansion history following the transition can be probed provided the transition is very strong which is naturally realised in classically scale invariant models generically predicting supercooling. Moreover, in such a scenario the decay rate of the scalar undergoing the phase transition, a parameter most likely inaccessible to accelerators, can be determined through the spectrum analysis.

    ↳ gr-qcastro-ph.COhep-phJHEP(2025)·13 citations
29. 29*

    Quantum decoherence of gravitational waves

    Hiroki Takeda🇯🇵 · Takahiro Tanaka🇯🇵

    The quantum nature of gravity remains an open question in fundamental physics, lacking experimental verification. Gravitational waves (GWs) provide a potential avenue for detecting gravitons, the hypothetical quantum carriers of gravity. However, by analogy with quantum optics, distinguishing gravitons from classical GWs requires the preservation of quantum coherence, which may be lost due to interactions with the cosmic environment causing decoherence. We investigate whether GWs retain their quantum state by deriving the reduced density matrix and evaluating decoherence, using an environmental model where a scalar field is conformally coupled to gravity. Our results show that quantum decoherence of GWs is stronger at lower frequencies and higher reheating temperatures. We identify a model-independent amplitude threshold below which decoherence is negligible, providing a fundamental limit for directly probing the quantum nature of gravity. In the standard cosmological scenario, the low energy density of the universe at the end of inflation leads to complete decoherence at the classical amplitude level of inflationary GWs. However, for higher energy densities, decoherence is negligible within a frequency window in the range $100\mathrm{Hz}\text{-}10^8\mathrm{Hz}$, which depends on the reheating temperature. In a kinetic-dominated scenario, the dependence on reheating temperature weakens, allowing GWs to maintain quantum coherence above $10^7\mathrm{Hz}$.

    ↳ gr-qchep-phhep-thquant-phPRD(2025)·16 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.