Wed·Aug 6, 2025Wednesday·August 6, 2025

1. 01*

   High-frequency gravitational waves from first-order phase transitions

   Wen-Yuan Ai🇦🇹

   First-order phase transitions in the early Universe are a well-motivated source of gravitational waves (GWs). In this Letter, we identify a previously overlooked GW production mechanism: gravitational transition radiation, arising from graviton emission by particles whose mass changes as they pass through expanding bubble walls. Unlike conventional sources such as bubble collisions or sound waves, this mechanism operates at the microscopic scale set by the Lorentz-contracted wall thickness, leading to GW emission at significantly higher frequencies. The resulting spectrum features a distinctive shape with a peak frequency redshifting to $f_{\mathrm{peak}}\sim T_0\sim 10^{10}\mathrm{Hz}$ where $T_0$ is the current temperature of the Universe. This mechanism is generic and is expected to operate similarly for domain walls and other relativistic interfaces.

   hep-phastro-ph.COgr-qchep-thPRD(2026)·9 citations
2. 02*

   Attenuation of the ultra-high-energy neutrino flux by dark matter scatterings

   Ivan Esteban🇪🇸 · Alejandro Ibarra🇩🇪

   A flux of ultra-high-energy (UHE) neutrinos, produced by astrophysical sources at cosmological distances, is anticipated to exist and reach Earth. In this paper, we investigate the impact on the total flux, energy spectrum, and arrival directions of UHE neutrinos of neutrino-dark matter (DM) scatterings. We study scatterings both in the intergalactic medium and in the Milky Way. We emphasize the complementarity among neutrino detectors at different latitudes, that can probe anisotropies induced by neutrinos scattering with the Milky Way DM halo. We also discuss that, with mild astrophysical assumptions, limits on the DM-$\nu$ scattering cross section can be placed even if the neutrino sources are unknown. Finally, we explore all this phenomenology with the recent UHE neutrino event KM3230213A, and place the corresponding limits on the DM-$\nu$ scattering cross section.

   hep-phastro-ph.COastro-ph.HEJCAP(2026)·5 citations
3. 03*

   Light scalar mesons in D^+, D_s^+ decays into three pseudoscalars

   L. Maiani🇮🇹 · A.D. Polosa🇮🇹 · V. Riquer🇮🇹

   In response to recent experimental findings from the BES III and LHCb collaborations concerning the decay of open charm mesons into three pseudoscalars, we present evidence suggesting that the lightest scalar mesons can be characterized as diquark-antidiquark states mixed with the next-to-light, q\bar q, scalar mesons through six-fermion, instanton-induced interactions.

   hep-phPRD(2025)·0 citations
4. 04*

   Quantum Bootstrap Approach to a Non-Relativistic Potential for Quarkonium systems

   Jairo Alexis Lopez🇨🇴 · Carlos Sandoval🇨🇴

   The quantum bootstrap method is applied to determine the bound-state spectrum of Quarkonium systems using a non-relativistic potential approximation. The method translates the Schrödinger equation into a set of algebraic recursion relations for radial moments $⟨r^m⟩$, which are constrained by the positive semidefiniteness of their corresponding Hankel matrices. The numerical implementation is first validated by calculating the $1S$ and $1P$ mass centroids for both charmonium ($c\bar{c}$) and bottomonium ($b\bar{b}$) systems, finding deviations of less than 0.5\% from experimental data from the Particle Data Group (PDG). This analysis is then extended to the hypothetical toponium ($t\bar{t}$) system, predicting a $1S$ ground state mass of $M\approx 344.3\text{ GeV}$. This theoretical mass is in agreement with the energy of the recently observed resonance-like enhancement in the $t\bar{t}$ cross-section by the ATLAS and CMS collaborations. This result provides theoretical support for the interpretation of this experimental phenomenon as the formation of a quasi-bound toponium state and highlights the predictive power of the non-relativistic potential approach for systems of two massive quarks.

   hep-phhep-lathep-thquant-ph5 citations
5. 05*

   Second-order renormalized Hamiltonian of Yukawa theory

   Kamil Serafin🇺🇸 · Carter M. Gustin🇺🇸 · Peter J. Love🇺🇸

   Using the renormalization group procedure for effective particles (RGPEP) we calculate the effective Hamiltonians in the theory of a fermion field coupled to a scalar field via the Yukawa interaction. The theory is renormalized by the addition of counterterms. Necessary counterterms are determined by computing matrix elements of the effective Hamiltonian. All calculations are performed up to the second order in the expansion in powers of the coupling constant. Renormalized effective Hamiltonians are well-defined symmetric forms acting in the Fock space as opposed to the renormalized bare Hamiltonian, which is not well-defined without regularization. We introduce computational techniques that should streamline higher-order calculations and may be of independent interest.

   hep-phnucl-thPRD(2025)·3 citations
6. 06*

   Probing non-perturbative QCD aspects on particle production in pp collisions with forward-backward correlations using \texttt{PYTHIA8}

   Rohit Agarwala🇮🇳 · Kalyan Dey🇮🇳

   We employ PYTHIA8 simulations to study forward-backward (FB) correlations in pp collisions at LHC energies, probing non-perturbative QCD dynamics via color reconnection (CR) and QCD radiation (ISR/FSR). Using \texttt{PYTHIA8} (v8.311) under ALICE/ATLAS kinematics, we analyze: extensive: FB multiplicity ($b_{\mathrm{corr}}^{\mathrm{mult}}$) and summed $p_{\mathrm{T}}$ ($b_{\mathrm{corr}}^{\sum p_{\mathrm{T}}}$) correlations; intensive: FB mean $p_{\mathrm{T}}$ ($b_{\mathrm{corr}}^{{\overline{p}}_{\mathrm{T}}}$) correlations; and \textit{strongly intensive:} ${\Sigma }_{{\mathrm{N}}_{\mathrm{F}}{\mathrm{N}}_{\mathrm{B}}}$ quantity in symmetric pseudorapidity intervals, validated against available experimental data. Systematic studies of $b_{\mathrm{corr}}^{\mathrm{mult}}$ as functions of ${\eta }_{\mathrm{gap}}$, ${\eta }_{\mathrm{sep}}$, and $\eta$-$\phi$ sectors show MPI-based CR (ranges 3.6, 5.4) and QCD Color Rope significantly improve agreement with data. ISR/FSR critically influence $b_{\mathrm{corr}}^{\mathrm{mult}}$ and $b_{\mathrm{corr}}^{\sum p_{\mathrm{T}}}$, with ISR dominant than FSR. Disabling ISR/FSR fails to replicate ${\eta }_{\mathrm{gap}}$-dependent trends. Further, $b_{\mathrm{corr}}^{\sum p_{\mathrm{T}}}$ shows minimal CR-range sensitivity but the correlation strength increases when CR is disabled. Intensive quantity, $b_{\mathrm{corr}}^{{\overline{p}}_{\mathrm{T}}}$, exhibit the opposite behavior to extensive observables i.e. the magnitude of $b_{\mathrm{corr}}^{{\overline{p}}_{\mathrm{T}}}$ increases with the increase of CR strength, highlighting the distinct influence of CR on intensive versus extensive observables. Its azimuthal dependence indicates that parton showers drive short-range correlations. The analysis of the strongly intensive quantity as a function of pseudorapidity gap indicates that FSR plays a dominant role at larger gaps, in contrast to the behavior observed in FB multiplicity correlations.

   hep-phnucl-th0 citations
7. 07*

   $\gamma ,J/\psi$ production through ISR process in electron-positron annihilation at B-factories

   Shashank Bhatnagar🇮🇳

   We study the Initial state radiation (ISR) process, $e^{-}{e}^{+}{\to }^{\ast }\gamma \to \gamma +J/\psi$ observed at high luminosity $e^{-}{e}^{+}$ colliders such as B-factories, with the ISR photon being emitted through the initial electron or positron, prior to their annihilation. The emitted $J/\Psi$ is produced through the photon fragmentation process, with the produced $J/\psi$ in turn decaying into a pair of leptons, ${\mu }^{-}+{\mu }^{+}$ through the leptonic decay process, $J/\Psi \to {\gamma }^{\ast }\to \gamma {\mu }^{-}{\mu }^{+}$. The cross section for the $J/\Psi$ production, and the branching ratio for the leptonic decay of $J/\Psi \to {\mu }^{-}{\mu }^{+}$, both calculated in the framework of Bethe-Salpeter equation are used to work out the cross section for the complete process, $e^{-}{e}^{+}\to \gamma +J/\psi \to \gamma +{\mu }^{-}+{\mu }^{+}$. Our results are compared with the BaBar data, and other models. This study is then extended to production and decays of ${\rm Y}(1S)$ through the ISR process.

   hep-phPRD(2025)·1 citation
8. 08*

   QCD sum rule study of topped mesons within heavy quark effective theory

   Shu-Wei Zhang🇨🇳 · Xuan Luo🇨🇳 · Hui-Min Yang🇨🇳 · Hua-Xing Chen🇨🇳

   Motivated by the recent CMS observation of a near-threshold enhancement in top quark pair production, we investigate a novel class of hadronic systems containing a single top quark: the topped mesons ($t\bar{q}$, with $\bar{q}=\bar{u},\bar{d},\bar{s}$). In contrast to the extensively studied toponium ($t\bar{t}$) system, analyzed primarily within perturbative QCD, topped mesons offer a complementary nonperturbative probe of QCD dynamics in the heavy quark limit. These states are expected to exhibit longer lifetimes and narrower decay widths than toponium, as only a single top quark undergoes weak decay. We employ QCD sum rules within the framework of heavy quark effective theory to study the structure and mass spectrum of ground-state topped mesons. Our analysis predicts masses near 173.1 GeV, approximately 0.5-0.6 GeV above the top quark pole mass. Compared with singly topped baryons ($tqq$, with $q=u,d,s$) studied concurrently in [arXiv:2507.05895], topped mesons have a simpler quark composition and more favorable decay channels (a topped meson is anticipated to decay weakly into a ${\rm Y}$ meson and a charmed meson), enhancing their potential for both theoretical analysis and experimental discovery.

   hep-phUniverse(2025)·11 citations
9. 09*

   Roles of $a_0(980)$ and $a_0(1710)$ in Cabibbo-suppressed process $D^{+}\to {\pi }^0{\pi }^{+}\eta$

   Xiao-Hui Zhang🇨🇳 · Jing-Yu Zhu🇨🇳 · Li-Juan Liu🇨🇳 · En Wang🇨🇳

   Motivated by the BESIII amplitude analysis of the single Cabibbo-suppressed process $D^{+}\to {\pi }^0{\pi }^{+}\eta$, we investigate this reaction by taking into account the contributions from the $a_0(980)$, $\rho$, and $a_0(1710)$, where the scalar meson $a_0(980)$ could be dynamically generated from the $S$-wave pseudoscalar meson-pseudoscalar meson interaction within the chiral unitary approach. Our theoretical predictions for the ${\pi }^0\eta$, ${\pi }^{+}\eta$, and ${\pi }^{+}{\pi }^0$ invariant mass distributions are in agreement with the BESIII measurements, especially the clear peaks around 1~GeV in the ${\pi }^0\eta$ and ${\pi }^{+}\eta$ invariant mass distributions could be associated with the dynamically generated state $a_0(980)$. Furthermore, we demonstrate that the intermediate $a_0(1710)$ is also necessary to describe the enhancement structure around $1.6\sim 1.7$~GeV in the ${\pi }^{0/+}\eta$ invariant mass distribution. More precise experimental measurements of this process could provide deeper insights into the nature of the scalar mesons $a_0(980)$ and $a_0(1710)$.

   hep-phPRD(2025)·1 citation
10. 10*

    Hyperon spin correlation in high-energy heavy-ion collisions

    Xin-Li Sheng🇮🇹 · Xiang-Yu Wu🇨🇦 · Dirk H. Rischke🇩🇪 · Xin-Nian Wang🇨🇳

    Recent experimental data show an unexpectedly large spin alignment of $\varphi$ mesons in high-energy heavy-ion collisions, which can be explained by short-distance fluctuations of strong-force fields (vector $\varphi$ fields) within the constituent-quark model. We calculate the hyperon spin correlations within the same model, taking into account hydrodynamic effects and a $\varphi$ field fluctuating in space-time according to a Gaussian distribution. The $\Lambda \bar{\Lambda }$ spin correlation induced by the $\varphi$ field is shown to be negative as opposed to that of $\Lambda \Lambda$ or $\bar{\Lambda }\bar{\Lambda }$. We thus propose a new net spin-correlation observable as a sensitive probe to separate strong-force effects from hydrodynamic ones. With the strength of the field fluctuations extracted from the observed $\varphi$ spin alignment, we predict the collision-energy dependence of the hyperon spin correlations and also investigate the dependence of the net spin correlation on azimuthal-angle and rapidity difference.

    hep-phnucl-thPRL(2026)·12 citations
11. 11*

    High-energy evolution in planar QCD to three loops: the non-conformal contribution

    Giacomo Brunello🇮🇹 · Simon Caron-Huot🇨🇦 · Giulio Crisanti🇬🇧 · Mathieu Giroux🇨🇦 · Sid Smith🇮🇹

    The Balitsky-Kovchegov (BK) equation offers a tractable description of the high-energy growth of gauge-theory scattering amplitudes and the nonlinear saturation effects that eventually tame it. Motivated by the upcoming Electron-Ion Collider (EIC), whose extended kinematic reach promises more decisive tests of saturation at high energies, we present a framework based on the spacelike-timelike correspondence that streamlines the computation of multi-loop corrections to the BK equation. We explicitly verify the correspondence at three loops in the large-flavor limit and predict the full nonconformal component of the three-loop BK Hamiltonian in the planar limit of a generic gauge theory, treating the numbers of fermions and scalars as free parameters.

    hep-phhep-thJHEP(2025)·16 citations
12. 12*

    Cosmic Axion Background Detection Using Resonant Cavity Arrays

    Soobeom Chung🇺🇸 · Jeff A. Dror🇺🇸

    The axion is a well-motivated and generic extension of the Standard Model. If produced in the early universe, axions may still be relativistic today, forming a Cosmic Axion Background (C$a$B) potentially detectable in direct detection experiments. Although C$a$B is expected to be broadband, which makes it challenging to be detected, a high-quality-factor microwave cavity acts as a narrowband filter with response peaked at its resonant frequency. We propose a new strategy using multi-cavity arrays to distinguish signal from background noise by exploiting spatial correlations of the axion-induced electric field which are set by the cavity quality factor. We compute the two-point correlation function for electric fields in spatially separated cavities sourced by an isotropic C$a$B. Analyzing various cavity geometries, we find that stacked, wide-base cavity arrays offer coherent enhancement of the axion signal. We apply our formalism to prospective upgrades of the ADMX experiment, including configurations with four and eighteen coupled cavities. Although these arrays do not achieve a coherent enhancement, optimizing the geometry could potentially yield an $\mathcal{O}(1)$ improvement in the sensitivity to the C$a$B.

    hep-phastro-ph.HEJHEP(2026)·0 citations
13. 13*

    Profiling Dark Matter Spikes with Gravitational Waves from Accelerated Binaries

    Avinash Tiwari🇮🇳 · Prolay Chanda🇮🇳 · Shasvath J. Kapadia🇮🇳 · Susmita Adhikari🇮🇳 · Aditya Vijaykumar🇨🇦 · Basudeb Dasgupta🇮🇳

    Dark matter halos can develop a density spike, e.g., around a galactic supermassive black hole, with the profile $\rho \propto r^{-{\gamma }_{\mathrm{sp}}}$ determined both by the galaxy's formation history and the microphysics of dark matter. We show that future LISA/DECIGO observations, of intermediate/stellar-mass binary mergers inside the spike around the supermassive black hole, can measure ${\gamma }_{\mathrm{sp}}$ at a few-percent--level precision. The spike induces a distinctive time-dependent acceleration along the non-circular orbit taken by the binary's center of mass, which is observable as a secular modulation of the gravitational wave signal. This method -- insensitive to confounding astrophysical effects (dynamical friction, tidal effects, etc.) and not reliant on unknown dark matter particle physics -- provides a clean diagnostic of density spikes and a new probe of dark matter.

    hep-phastro-ph.COastro-ph.HE7 citations
14. 14*

    Bounding anisotropic Lorentz Invariance Violation from measurements of the effective energy scale of quantum gravity

    Merce Guerrero🇵🇹 · Anna Campoy-Ordaz🇪🇸 · Robertus Potting🇵🇹 · Markus Gaug🇪🇸

    Observations of energy-dependent photon time delays from distant flaring sources provide significant constraints on Lorentz Invariance Violation (LIV). Such effects originate from modified vacuum dispersion relations, causing differences in propagation times for photons emitted simultaneously from gamma-ray bursts, active galactic nuclei, or pulsars. These modifications are often parametrized within a general framework by an effective quantum gravity energy scale $E_{QG,n}$. While such general constraints are well established in the LIV literature, their translation into specific coefficients of alternative theoretical frameworks, such as the Standard-Model Extension (SME), is rarely carried out. In particular, existing bounds on the quadratic case ($n=2$) of $E_{QG,n}$ can be systematically converted into constraints on the non-birefringent, CPT-conserving SME coefficients $c_{(I)jm}^{(6)}$. This work provides a concise overview of the relevant SME formalism and introduces a transparent conversion method from $E_{QG,2}$ to SME parameters. We review the most stringent time-of-flight-based bounds on $E_{QG,n}$ and standardize them by accounting for systematics, applying missing prefactors, and transforming results into two-sided Gaussian uncertainties where needed. We then use these standardized constraints, along with additional bounds from the literature, to improve bounds on the individual SME coefficients of the photon sector by about an order of magnitude. A consistent methodology is developed to perform this conversion from the general LIV framework to the SME formalism.

    ↳ astro-ph.HEgr-qchep-phPRD(2025)·3 citations
15. 15*

    Lattice results for the equation of state in dense QCD-like theories

    Etsuko Itou🇯🇵

    We review recent progress in Monte Carlo simulations of dense two-color QCD (QC${}_2$D), focusing on the phase diagram, the equation of state, and the sound velocity in the low-temperature regime. In three-color QCD at finite density, especially at low temperatures, the notorious sign problem makes lattice Monte Carlo simulations intractable. In contrast, QC${}_2$D is free from this issue due to the pseudoreality of the quark representation. Recent independent lattice studies have revealed unexpected phenomena through first-principles calculations of the phase structure and thermodynamics. A particularly notable finding is that the sound velocity exceeds the so-called conformal (holography) bound, \( c_s^2/c^2 \le 1/3 \), which had not been observed in QCD-like theories at finite temperature. In this review, we focus primarily on results from a series of works by our group~\cite{Iida:2019rah, Iida:2020emi,Iida:2022hyy, Ishiguro:2021yxr, Iida:2024irv}, along with related studies in dense QC${}_2$D and three-color QCD with isospin chemical potential. We discuss the possibility and physical implications of conformal bound violation even for three-color dense QCD, together with insights from effective model analyses and recent observations of neutron stars.

    ↳ hep-lathep-phhep-thnucl-thUniverse(2025)·11 citations
16. 16*

    New computational methods in lattice gauge theory -- quantum computation and tensor networks

    Etsuko Itou🇯🇵

    Lattice QCD calculations have been conducted using large-scale classical computers based on the Lagrangian formalism of field theory for the past 40 years. On the other hand, the advent of quantum computers has brought increasing attention to first-principles computational methods based on the Hamiltonian formalism compatible with these machines. In this talk, we discuss recent results on how to calculate hadronic properties using the Hamiltonian formalism.

    ↳ hep-lathep-phnucl-thquant-phPoS(2026)·2 citations
17. 17*

    Photon polarization tensor in presence of constant and arbitrary electric field

    Luis A. Hernández🇲🇽 · Juan D. Martínez-Sánchez🇲🇽 · R. Zamora🇨🇱

    We compute the photon polarization tensor at one-loop order in the presence of a constant and uniform electric field. Our calculation is carried out for arbitrary field strength using the Schwinger proper-time formalism, and we explicitly derive an expression for the polarization tensor without approximations. We also present a complementary derivation within the strong field approximation. Our main contribution lies in expressing the polarization tensor in terms of a physically motivated tensor basis that ensures transversality and thus preserves gauge invariance. This basis, constructed from the preferred direction defined by the external electric field, makes explicit the breaking of Lorentz symmetry. We verify the consistency of our results by recovering the well-known vacuum polarization tensor in the zero-field limit and by demonstrating agreement between the strong field limit of the general expression and the result obtained directly in the strong field approximation. Interestingly, in the latter case, only one tensor structure survives, corresponding to the transverse dynamics with respect to the field direction, which highlights the dominance of perpendicular modes.

    ↳ hep-thhep-phEPJC(2026)·1 citation
18. 18*

    Nonlinear analysis of causality for heat flow in heavy-ion collisions: constraints from equation of state

    Victor Roy🇮🇳

    The present work investigates the causal parameter space of the Mueller-Israel-Stewart second-order theory for heat-conducting fluids in the Eckart frame for one-dimensional fluid flow in systems with finite baryon density. It is shown that this parameter space is highly constrained and particularly sensitive to the equation of state and second-order transport coefficients. Through numerical analysis of the characteristic equations, the present analysis identifies regions of strong hyperbolicity, weak hyperbolicity, and non-hyperbolicity, mapping the boundaries of causality violation as functions of the heat flux to energy density ratio $q/\epsilon$ and relaxation parameters. The present work also explores the causality conditions using a realistic lattice QCD-based equation of state. Using the Navier-Stokes approximation, an estimate is made of the heat flow magnitude to assess causality criteria for one-dimensional heat conduction in heavy-ion collisions. The present calculations reveal unrealistically large heat flux values ($|\mathbf{q}|/\epsilon \approx 330$--$811$) for typical RHIC conditions when using thermal conductivity estimates from kinetic theory models, suggesting either significant overestimation of transport coefficients or breakdown of the fluid approximation in these extreme conditions. The pressure gradient corrections reduce the heat flow by approximately 15\% but do not resolve the causality concerns.

    ↳ nucl-thhep-phPRC(2026)·2 citations
19. 19*

    Theoretical framework for lattice QCD computations of $B\to K{\ell }^{+}{\ell }^{-}$ and ${\bar{B}}_s\to {\ell }^{+}{\ell }^{-}\gamma$ decays rates, including contributions from charming penguin diagrams

    R. Frezzotti🇮🇹 · G. Gagliardi🇮🇹 · V. Lubicz🇮🇹 · G. Martinelli🇮🇹 · C.T. Sachrajda🇬🇧 · F. Sanfilippo🇮🇹 · L. Silvestrini🇮🇹 · S. Simula🇮🇹 · N. Tantalo🇮🇹

    We develop a strategy for computing the $B\to K{\ell }^{+}{\ell }^{-}$ and ${\bar{B}}_s\to \gamma {\ell }^{+}{\ell }^{-}$ decay amplitudes using lattice QCD (where ${\ell }^{\pm }$ are charged leptons). We focus on those terms which contain complex contributions to the amplitude, due to on-shell intermediate states propagating between the weak operator and electromagnetic current(s). Such terms, which are generally estimated using model calculations and represent significant uncertainties in the phenomenological predictions for these decays, cannot be computed using standard lattice QCD techniques. It has recently been shown that such contributions can be computed using spectral-density methods and our proposed strategy, which we discuss in detail, is built on this approach. The complex contributions include the ``charming penguins" (matrix elements of the current-current operators $O_1^{(c)}$ and $O_2^{(c)}$ defined in Eq. (6) below), in which the charm-quark loop can propagate long distances, particularly close to the region of charmonium resonances. They also include the contributions from the chromomagnetic operator ($O_8$ in standard notation, defined in Eq. (8) below). We discuss the renormalization of the ultra-violet divergences, and in particular those which arise due to ``contact" terms, and explain how those which appear as inverse powers of the lattice spacing can be subtracted non-perturbatively. We apply the spectral density methods in an instructive exploratory computation of the charming penguin diagram in $B\to K{\ell }^{+}{\ell }^{-}$ decays in which the virtual photon is emitted from the charm-quark loop (the diagram in Fig. 1(a) below) and discuss the prospects and strategies for the reliable determination of the amplitudes in future dedicated computations; computations which are however, beyond the scope of the present paper.

    ↳ hep-lathep-phPRD(2026)·16 citations
20. 20*

    Hot New Early Dark Energy: Dark Radiation Matter Decoupling

    Mathias Garny🇩🇪 · Florian Niedermann🇸🇪 · Henrique Rubira🇩🇪 · Martin S. Sloth🇩🇰

    We present a microscopic model of the dark sector that resolves the Hubble tension within standard current datasets based on well-known fundamental principles, gauge symmetry and spontaneous symmetry breaking. It builds on the Hot New Early Dark Energy (Hot NEDE) setup, featuring a dark $SU(N)$ gauge symmetry broken to $SU(N-1)$ in a supercooled phase transition that creates a thermal bath of self-interacting dark radiation in the epoch between Big Bang Nucleosynthesis and recombination. Adding a fermion multiplet charged under the gauge symmetry provides a naturally stable component of dark matter that interacts with dark radiation. Spontaneous symmetry breaking predicts a decoupling of this interaction once the dark sector cools down, that we refer to as dark radiation matter decoupling (DRMD). We find agreement between the SH${}_0$ES determination of $H_0$ as well as combined Planck 2018, Pantheon+ and DESI baryon acoustic oscillation (BAO) data at 1.4$\sigma$ level, compared to a 5.7$\sigma$ tension in the $\Lambda$ Cold Dark Matter model. We also provide a simplified three-parameter DRMD model encoding the essential features, while the full model offers additional falsifiable predictions.

    ↳ astro-ph.COhep-phhep-thPRD(2026)·20 citations
21. 21*

    Effects of light-mass fermionic dark matter on the equilibrium and stability of white dwarfs

    G.A. Carvalho🇧🇷 · J.D.V. Arbañil🇵🇪 · J.G. Coelho🇧🇷

    White dwarfs (WDs) can be used as laboratories to test strong gravity and high-density regimes, once their equation of state is not so uncertain as the one of neutron stars. This makes them also a useful tool to constrain dark-matter models. In this work, we study dark matter white dwarfs (DMWD) composed of white dwarf matter admixed with fermionic dark matter in a two-fluid general relativistic framework. Dark matter particles are considered to have masses between $0.1-10$ GeV. The equilibrium configurations and stability are derived, showing that the DMWD can be more compact, with masses around 1.3 $M\odot$ and radii around 500 km. The increasing compactness leads to changes in the fundamental modes of radial oscillations ($\sim 20\%$ for 0.1 GeV DM), which produce detectable shifts in GW frequencies. The interplay between dark matter and normal matter thus provides a compelling avenue for interpreting deviations in observed WD properties and for placing constraints on DM characteristics through astrophysical observations.

    ↳ astro-ph.HEastro-ph.SRgr-qchep-ph+1PRD(2025)·1 citation

* 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.