Wed·Sep 17, 2025Wednesday·September 17, 2025

1. 01*

   Leptogenesis from Dark Matter Coannihilation

   Simran Arora🇮🇳 · Debasish Borah🇮🇳 · Arnab Dasgupta🇺🇸 · P. S. Bhupal Dev🇺🇸 · Devabrat Mahanta🇮🇳

   We propose a minimal extension of the type-I seesaw model to realise leptogenesis from the co-annihilation of dark sector particles. The type-I seesaw model is extended with a singlet fermion and two singlet scalars charged under a $Z_2$ symmetry. The $Z_2$-odd singlet scalar is the dark matter candidate. Here the usual type-I seesaw mechanism generates neutrino mass, and a net lepton asymmetry is generated from the co-annihilation of the dark matter and the $Z_2$-odd singlet fermion. The $Z_2$-even singlet scalar is important in dark matter phenomenology. Successful leptogenesis is possible at TeV-scale, unlike the vanilla case. This minimal extension provides an elegant explanation of successful leptogenesis with direct connection to the dark matter abundance in the Universe.

   hep-phastro-ph.COJCAP(2026)·2 citations
2. 02*

   Dynamical Mass Generation in QED: Miransky scaling and Schrödinger-like infinite well and barrier potentials supporting a bound state

   Juan D. García-Muñoz🇲🇽 · A. Alfaro🇲🇽 · L. X. Gutiérrez-Guerrero🇲🇽 · A. Raya🇲🇽

   In this study, we revisit the Schwinger-Dyson equation for the electron propagator in QED in three and four space-time dimensions. Our analysis addresses the non-perturbative phenomenon of dynamical chiral symmetry breaking, which requires a critical value of the coupling for the dynamical generation of electron masses, encoded in the infrared behavior of the corresponding Green function. With a minimalistic truncation of the infinite tower of equations and adopting standard assumptions, the resulting gap equation is linearized and transformed into a Schrödinger-like equation with an auxiliary potential barrier (or well) subjected to boundary conditions for both high and low momenta. The dynamical mass is then associated with the zero mode of the corresponding Schrödinger-like operator and follows the Miransky scaling law, as expected.

   hep-phhep-thFew Body Syst.(2025)·0 citations
3. 03*

   Probing Flavour Deconstruction via Primordial Gravitational Waves

   Noemi Fabri🇨🇭 · Gino Isidori🇨🇭 · Davide Racco🇨🇭

   We study the production of primordial gravitational waves (GWs) from first-order phase transitions (FOPTs) in extensions of the Standard Model based on Flavour Deconstruction (FD). The link fields inherent to FD generically form a rich scalar sector, with sizeable couplings at the TeV scale, providing natural conditions for strong FOPTs and correspondingly large GW emission. We identify the key parameters controlling the GW spectrum and enabling its detection at future GW observatories. In particular, we find that while FD scenarios can yield detectable signals, the resulting spectra typically peak at higher frequencies than the millihertz range. As a consequence, a positive observation at LISA is possible but not guaranteed, while the signal falls in the range of mid-band proposals, making FD models an intriguing target for upcoming GW searches.

   hep-phastro-ph.CO7 citations
4. 04*

   Observing Double Higgs Production at the LHC via Neutrino Feature Engineering in $hh\to b\bar{b}\ell \ell \nu \nu$

   Alexandre Alves🇧🇷 · Eduardo da Silva Almeida🇧🇷 · Diego S. V. Gonçalves🇧🇷

   Double Higgs production is challenging even at the High Luminosity LHC. The Standard Model (SM) $hh\to b\bar{b}WW(ZZ)\to b\bar{b}\ell \ell \nu \nu$ has a moderate cross section compared to other decay modes, but its backgrounds, mainly top quark pairs and Drell-Yan production, are overwhelming. In this work, we propose new kinematic features designed to improve the discrimination of double Higgs pairs, in the $b\bar{b}\ell \ell \nu \nu$ channel, with cut-based and multivariate analyses. The new features are built with the neutrinos' momenta solutions obtained from imposing mass constraints when calculating Higgsness and Topness variables. For the SM $hh$ production, we estimate a $3.7\sigma$ statistical significance from an optimized cut-based strategy, improving about 20% over the best estimates of the literature, and $5\sigma$ from a multivariate analysis if systematic uncertainties on the backgrounds are small. The new variables are constructed as ratios of kinematic functions of the particles' momenta, being less prone to systematic errors. We also demonstrate the usefulness of the solutions in reconstructing heavy scalar resonances and other variables of phenomenological importance.

   hep-phhep-exEPJC(2026)·1 citation
5. 05*

   Searching for leptophilic composite asymmetric dark sector at $e^{+}{e}^{-}$ colliders

   Chih-Ting Lu🇨🇳 · Changbin Xi🇨🇳

   Composite asymmetric dark matter (ADM) models provide a well-motivated paradigm that simultaneously explains dark matter (DM) relic density and matter-antimatter asymmetry. In these models, the mass of the DM candidate (the lightest dark baryon) is generated through the dark confinement scale dynamics. Although the leptophilic composite ADM model offers a viable framework, comprehensive studies of its collider phenomenology are absent. This work systematically explores novel signatures from the leptophilic composite asymmetric dark sector at both low-energy and high-energy $e^{+}{e}^{-}$ colliders as well as other existing collider constraints. We demonstrate detectability of TeV-scale mediators along with sub-GeV to GeV-scale lightest dark mesons at Belle II and its proposed far detector, GAZELLE, as well as Circular Electron Positron Collider/Future Circular Collider-electron-positron experiments. Moreover, these experiments exhibit complementary coverage of the model parameter space.

   hep-phhep-exPRD(2025)·3 citations
6. 06*

   On the (Im)possibility of Electrically Charged Planck Relics

   Stefano Profumo🇺🇸

   I revisit whether black-hole remnants, from sub-Planckian compact objects to Planck relics and up to (super)massive black holes, can preserve Standard-Model (SM) electric charge. Two exterior-field mechanisms -- Coulomb-focused capture from ambient media and QED Schwinger pair production -- robustly neutralize such objects across cosmic history. I first derive the general capture rate including both Coulomb and gravitational focusing, and sum the stepwise discharge time in closed form via the trigamma function, exhibiting transparent Coulomb- and gravity-dominated limits. I then integrate the Schwinger rate over the near-horizon region to obtain an explicit $\dot{Q}(Q)$ law: discharge proceeds until the horizon field falls below $E_{\mathrm{crit}}$, leaving a residual charge $Q_{\mathrm{stop}}^{(e)}\propto r_h^2$ that is $\ll e$ for Planck radii. Mapping the mass dependence from sub-Planckian to astrophysical scales, I also analyze dark-sector charges with heavy carriers (including kinetic mixing and massive mediators). In a conservative ``no-Schwinger'' limit where vacuum pair creation is absent, cumulative ambient exposures alone force discharge of any integer SM charge. Three possible loopholes remain. (i) A fine-tuned SM corner in which the relic sits arbitrarily close to Reissner-Nordström extremality so greybody factors suppress charged absorption, while Schwinger pair creation is absent due to Planck-scale physics. (ii) Charge relocated to a hidden $U(1{)}_D$ with no light opposite carriers, e.g. if the lightest state is very heavy and/or kinetic mixing with $U(1{)}_{\mathrm{EM}}$ is vanishingly small. (iii) Discrete or topological charges rather than ordinary SM electric charge. Outside these cases, the conclusion is robust: within SM electromagnetism, charged black-hole relics neutralize efficiently and cannot retain charge over cosmological times.

   hep-phastro-ph.COastro-ph.HEgr-qc+1JCAP(2025)·1 citation
7. 07*

   Shedding light on the nature of $\varphi (2170)$ state in the $e^{+}{e}^{-}\to \varphi {\pi }^{+}{\pi }^{-}$ reaction

   Xiang Wei🇨🇳 · Qing-Hua Shen🇨🇳 · Xiao-Hai Liu🇨🇳 · Ju-Jun Xie🇨🇳

   We investigate the production of $\varphi (2170)$ state in the $e^{+}{e}^{-}\to \varphi {\pi }^{+}{\pi }^{-}$ reaction with the effective Lagrangian approach. In addition to the tree level contributions from the $\varphi (1680)$ meson and a possible X(1750) state, we consider also the $K_1$-$K$-$\bar{K}$ intermediate state process from the perspective of triangular singularity. Based on the one-photon exchange approximation, a pair of $K_1\bar{K}$ mesons was firstly produced, and then the $K_1$ meson subsequently decays into $\varphi$ and $K$, and the $K\bar{K}$ pair produce the ${\pi }^{+}{\pi }^{-}$ through the final state interactions, in which the scalar meson $f_0(980)$ is dynamically generated. We show that the inclusion of the triangle loop diagrams leads to a good description of the new BESIII measurements, especially for the structure of $\varphi (2170)$. This provides a novel interpretation of the $\varphi (2170)$ state, offering new insights into its fundamental nature which is still unclear. Furthermore, it is found that these measurements on the $e^{+}{e}^{-}\to \varphi {\pi }^{+}{\pi }^{-}$ reaction can be used to determine some of the properties of two $K_1$ mesons with masses around 1610 MeV and 1895 MeV, which are crucial to reproduce the experimental data.

   hep-phPRD(2026)·4 citations
8. 08*

   Cabibbo-suppressed charged-current semileptonic decays of ${\Xi }_b$ baryons

   Zhou Rui🇨🇳 · Zhi-Tian Zou🇨🇳 · Ya Li🇨🇳 · Ying Li🇨🇳

   We present the first perturbative QCD calculations of the ${\Xi }_b\to (\Lambda ,\Sigma )$ transition form factors at leading order in ${\alpha }_s$, which govern the Cabibbo-suppressed semileptonic decays ${\Xi }_b\to (\Lambda ,\Sigma )\ell {\nu }_{\ell }$ with $\ell =e,\mu ,\tau$. Using these form factors, we evaluate differential and integrated branching fractions and angular observables within the helicity formalism. The branching ratios are predicted to be of order $10^{-4}$ for $\Sigma$ final states and $10^{-5}$ for $\Lambda$ final states, making them accessible to ongoing experiments such as LHCb. Ratios of decay rates between $\tau$ and $e$ channels are also provided, offering new probes of lepton-flavor universality. Lepton-mass effects are found to significantly impact the integrated angular observables. Furthermore, a combined analysis of $b\to u$ and $b\to c$ transitions in ${\Xi }_b$ decays yields sub-percent precision for the ratios ${\mathcal{R}}_{\ell }(\Sigma /{\Xi }_c)$, enabling an independent determination of $|V_{ub}/V_{cb}|$ once the relevant decay-rate measurements become available.

   hep-phPRD(2025)·2 citations
9. 09*

   Strangeness production in $p$Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV in the PACIAE model

   Wei Lei🇨🇳 · Qiang Wang🇨🇳 · An-Ke Lei🇨🇳 · Zhi-Lei She🇨🇳 · Jia-Xin Gao🇨🇳 · Dai-Mei Zhou🇨🇳 · Yu-Liang Yan🇨🇳 · Hua Zheng🇨🇳 · Wen-Chao Zhang🇨🇳 · Ben-Hao Sa🇨🇳

   We present a study of the single- and multi-strange particle productions in $p$Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV using the PACIAE 4.0 model. The effects of the color reconnection (CR), rope hadronization (RH) as well as the partonic and hadronic rescatterings (PRS and HRS) on their productions are investigated, respectively. There are two kinds of CR considered: the multiparton interactions-based CR (MPI-CR) and the quantum chromodynamics-based CR (QCD-CR). The four mechanisms studied have little effect on kaon production. However, the QCD-CR scheme incorporating the junction topology gives an enhanced baryon production, but it is still not enough to describe the integrated yields of strange baryons. The combination of QCD-CR and RH scheme together with the flavor ropes (FR) and the string shoving (SS), i.e., QCD-CR+FR+SS, provides a good description of the production of strange baryons. PRS has a weak effect but HRS exerts a promoting effect on the production of multi-strange baryons ($\Xi$ and $\Omega$).

   hep-phhep-thPRC(2026)·1 citation
10. 10*

    Probabilities in Toy Regge models with odderons

    M.A.Braun🇷🇺

    The possibi;lity of a probabilistic interpretation is studied for the Regge-Gribov model in zero dimensional transverse world ("Toy") with interacting pomerons and odderons. It is found that the previously proposed recipe to introduce such interpretation in the model without odderons, does not work once odderons are included. Starting from the physically reasonable probabilites it leads to a pathological field theory violating $C$-parity invariance. Inversely, starting from an admissible field theory one comes to pathological probabilities, which not only violate $C$-nvariance but also allow particles to be created from or annihilated into the vacuum. A method is proposed to introduce reasonable probabilities besed directly on the Fock components of the wave function. Such probabilities manifest themselves in the multiplicity distributions of hadrons produced in high-energy collisions. The corresponding entropy grows with rapidity but saturates in the limit. It is found to be similar for processes of both parity exchanges.

    hep-phEPJC(2025)·0 citations
11. 11*

    One-loop Renormalization of the Type-I Seesaw Model in the On-shell Scheme

    Jihong Huang🇨🇳 · Shun Zhou🇨🇳

    In this paper, we continue to carry out the one-loop renormalization of the type-I seesaw model in the on-shell scheme. Different from the modified minimal-subtraction ($\overline{\mathrm{MS}}$) scheme, such an investigation is mainly motivated by the fact that the on-shell scheme has been widely adopted in the renormalization of the standard electroweak theory and implemented for its precision tests. We first specify the physical parameters in the on-shell scheme, and then fix the corresponding counterterms through on-shell renormalization conditions. In the presence of massive Majorana neutrinos, we propose a practical method to determine gauge-independent counterterms for the lepton flavor mixing matrix. With the explicit counterterms in both the $\overline{\mathrm{MS}}$ and on-shell schemes, we establish the matching relations of the electric charge, physical masses and flavor mixing matrix elements between these two schemes. Our results in the present and previous papers lay the foundation for precision calculations in the type-I seesaw model.

    hep-phhep-exNPB(2026)·2 citations
12. 12*

    Electric Dipole Moments from Axion-Like Particle Dark Matter Background

    Jason L. Evans🇨🇳 · Nan Li🇨🇳 · Junyuan Lyu🇨🇳

    New one- and two-loop contributions to the lepton's and nucleon's EDM, which are induced by an axion-like particle dark matter background, are examined. These contributions include effects from CP-violating ALP interactions with photons, leptons and nucleons. The contribution to the EDM is so larger it leads to new constraints on the CP violating couplings of axion-like particles, if the axion-like particle mass is smaller than $10^{-11}$ eV.

    hep-ph2 citations
13. 13*

    Coupled-channel analysis for vector charmonia and their nature

    Satoshi X. Nakamura (Shandong University)🇨🇳

    High-precision $e^{+}{e}^{-}\to c\bar{c}$ data (20 final states) from the BESIII and Belle in $\sqrt{s}=3.75-4.7$ GeV are analyzed with a semi three-body unitary coupled-channel model. Vector charmonium poles are extracted from the amplitudes obtained from the fit. We find well-known $\psi$ states listed in the PDG, and also several states near open-charm thresholds. The compositeness of the near-threshold poles suggests that $\psi (4040)$ could mainly consist of a $D^{\ast }{\bar{D}}^{\ast }$-molecule component, rather than a conventionally accepted quark-model $\psi (3S)$ state. Also, $\psi (4230)$ and $\psi (4360)$ might be substantial mixtures of $D_1(2420)\bar{D}$, $D_1(2420){\bar{D}}^{\ast }$, $D_s^{\ast }{\bar{D}}_s^{\ast }$, and $c\bar{c}$ components.

    hep-phhep-exnucl-thJUSTC 55, 1207 (2025)·0 citations
14. 14*

    Partonic structure of nuclei from UPCs

    V. Guzey (Jyvaskyla U. and Helsinki Inst. of Phys.)🇫🇮

    We present an overview of theoretical and phenomenological studies on the partonic structure of nuclei and small-$x$ QCD dynamics using photon-nucleus $(\gamma A$) scattering in heavy ion ultraperipheral collisions (UPCs). Focusing on nuclear shadowing, we review implications of coherent charmonium and inclusive dijet production in Pb-Pb UPCs at the LHC and discuss the potential of inelastic $\gamma A$ scattering accompanied by forward neutrons in a zero degree calorimeter (ZDC).

    hep-phhep-exnucl-ex1 citation
15. 15*

    Perturbative QCD below charm threshold: theory and tensions with $e^{+}{e}^{-}$ data

    Diogo Boito🇧🇷 · Marcelle Caram🇧🇷

    In this paper we carefully assess the theory prediction for $R(s)$ below charm threshold, $R_{uds}$, and address tensions with the existing data, notably with the 2021 BES-III results. We analyze the uncertainty of the perturbative QCD description in the light of renormalons making use of the large-${\beta }_0$ limit and the renormalon-free gluon-condensate scheme. We provide a reliable estimate of the duality violation contributions; we show they are sizable up to $2.5$~GeV and improve the agreement between theory and data, but are negligible for higher energies. We then combine the available experimental data for $R_{uds}$ and find the data sets to be mutually compatible. Finally, we compare theory and data, both locally and in their contributions to the anomalous magnetic moment of the muon. Theory is compatible with the combined data but discrepancies with the BES-III data reach more than 3$\sigma$.

    hep-phhep-exPRD(2025)·3 citations
16. 16*

    Nuclear Suppression in Diffractive Vector Meson Production within the Color Glass Condensate Framework

    Heikki Mäntysaari🇫🇮 · Hendrik Roch🇺🇸 · Farid Salazar🇺🇸 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸

    We extend a recent global Bayesian analysis of diffractive $\mathrm{J}/\psi$ production in $\gamma +p$ and $\gamma +\mathrm{Pb}$ collisions within the color glass condensate (CGC) framework to investigate potential modifications of the nucleon structure inside nuclei. To this end, we perform fits that allow the effective nucleon structure parameters in Pb nuclei to differ from those of free protons. This approach directly addresses the question of whether the proton's spatial gluon distribution at intermediate to large $x$ is modified in the nuclear environment. We compare results obtained with shared and independent nucleon structure parameters and assess the impact on the simultaneous description of $\gamma +p$ data from HERA and the LHC, as well as $\gamma +\mathrm{Pb}$ data from the LHC. Our findings show that there is no hint of difference in the nucleon structure beyond those already present in the CGC when embedding nucleons inside a nuclear environment.

    hep-phnucl-th2 citations
17. 17*

    Born-Oppenheimer EFT: a unified description of ordinary and exotic quarkonia

    Antonio Vairo🇩🇪

    We show how the Born-Oppenheimer effective field theory (BOEFT) provides a unified description of ordinary and exotic quarkonia grounded on the non-relativistic expansions of QCD and supplemented with lattice QCD inputs. We apply BOEFT to tetraquarks, pentaquarks, quarkonium hybrids and to assess threshold effects in the quarkonium spectrum.

    hep-phhep-exPoS(2026)·0 citations
18. 18*

    Cogenesis of baryon and lepton number asymmetries matching the EMPRESS Data

    Kyu Jung Bae🇰🇷 · Arghyajit Datta🇰🇷 · Rinku Maji🇰🇷 · Wan-Il Park🇰🇷

    We show that a simple supersymmetric $U(1{)}_{B-L}$ extension of the standard model can explain simultaneously the large electron neutrino asymmetry hinted by the recent EMPRESS data as well as the observed tiny baryon asymmetry via the resonant leptogenesis mechanism. The condensation of $B-L$ Higgs dominating the universe at its decay is the sole source for these generation processes. Here, the infrequent decays of the $B-L$ Higgs to heavy right-handed neutrinos and successive prompt decays of these right-handed neutrinos around the electroweak phase transition produce the observed baryon asymmetry while the complete decay of the same $B-L$ Higgs at a later epoch leads to a large lepton number asymmetry. The right amounts of both asymmetries are found to be obtained for the symmetry breaking scale $v_{\varphi }\sim 10^{10}\mathrm{GeV}$. Moreover, in a close connection to the positivity of both asymmetries, seemingly only the normal mass hierarchy of light neutrino species works. Finally, the gravitational wave background from the topologically stable strong type-I cosmic strings, generated from the breaking of $U(1{)}_{B-L}$ symmetry, can be within the reach of future experiments such as ultimate DECIGO.

    hep-phastro-ph.COJCAP(2026)·3 citations
19. 19*

    Searching for heavy resonances via oblique parameters in non-linear effective frameworks

    Ignasi Rosell🇪🇸 · Antonio Pich🇪🇸 · Juan Jose Sanz-Cillero🇪🇸

    Within the framework of a general non-linear effective field theory describing the electroweak symmetry breaking, we perform a detailed analysis of the next-to-leading contributions to the electroweak oblique parameters $S$ and $T$ from hypothetical heavy resonance states strongly coupled to Standard Model fields. This work extends our previous results by including parity-odd operators in the effective Lagrangian, contributions from fermionic cuts, and up-to-date experimental constraints. We demonstrate that in strongly-coupled ultraviolet completions satisfying both Weinberg Sum Rules -- as is the case in asymptotically free gauge theories -- the vector and axial-vector resonance masses are constrained to lie above $10$TeV. Conversely, scenarios allowing for lighter resonances with masses between $2$and $10$TeV necessarily imply a violation of the second Weinberg Sum Rule.

    hep-phPoS(2026)·0 citations
20. 20*

    Probing Geometrical NSI at the DUNE experiment

    Riya Barick🇮🇳 · Indrajit Ghose🇮🇳 · Srubabati Goswami🇮🇳 · Amitabha Lahiri🇮🇳 · Sushant K. Raut🇮🇳

    In this work, we investigate the implications of a novel non-standard interaction (NSI) of neutrinos. This interaction is geometric in origin -- it arises because the propagation of fermions in curved spacetime induces torsion. This torsion is non-propagating and can be eliminated from the action, resulting in a four-fermion interaction in a torsion-free background. The new interaction modifies the behaviour of the neutrinos passing through matter by introducing additional coupling terms, resulting in a new component in the effective potential. As a result, the neutrino oscillation probabilities in matter are altered. The relevant probabilities are computed using the Cayley-Hamilton formalism. We then numerically explore the potential to probe these torsion-induced NSI in the DUNE experiment. We obtain the bounds on the parameters characterizing the torsional effects. By selecting representative values of torsion parameters to which the DUNE experiment is sensitive, we analyse how these geometric interactions affect the experiment's sensitivity to determine neutrino mass hierarchy, the octant of the 2-3 leptonic mixing angle, and the CP phase. We also examine the new parameter degeneracies introduced by torsion effects and assess their impact on the overall sensitivities of DUNE. We find that the additional parameter degeneracies in the presence of torsion significantly affect the octant sensitivity.

    hep-phJHEP(2026)·2 citations
21. 21*

    Smallness of neutrino masses and leptogenesis in 331 composite Higgs model

    Roman Nevzorov🇷🇺

    We consider 331 composite Higgs model (CHM3) in which the Lagrangian of the strongly coupled sector is invariant with respect to global SU(3)_C \times SU(3)\times U(1)_6 symmetry that can originate from SU(6) subgroup of E_6 and contains the gauge group of the standard model (SM) as a subgroup. The breakdown of the approximate SU(3)\times U(1)_6 symmetry down to SU(2)_W\times U(1)_Y subgroup around the scale f\sim 10 TeV results in a set of pseudo--Nambu--Goldstone bosons (pNGBs) that, in particular, involves Higgs doublet. The generation of the masses of the SM fermions in the CHM3 is discussed. We argue that approximate U(1)_L and discrete Z_2 symmetries may give rise to tiny masses of the left--handed neutrinos and several composite fermions with masses 1-2 TeV. The lepton and baryon asymmetries can be generated within the CHM3 via the out--of equilibrium decays of extra Majorana particle into the Higgs doublet and these composite fermions.

    hep-phgr-qchep-exhep-lat+1PLB(2026)·2 citations
22. 22*

    Revisiting axion dark matter with nonlinear transitions

    Max Miyazaki🇯🇵 · Yuma Narita🇯🇵 · Deheng Song🇯🇵 · Nemin Yaginuma🇯🇵 · Wen Yin🇯🇵

    Recently, two of the present authors showed that even when the axion momentum is much smaller than its mass, the axion can still behave like radiation if its energy density greatly exceeds the maximum potential energy set by the cosine-type potential. As the energy density redshifts down to the potential scale, a nonlinear transition occurs, during which the axion's adiabatic invariant is not conserved. In this paper, we revisit the analysis of axion dark matter by incorporating the effects of this nonlinear transition through a precise study of the axion spectrum. We demonstrate that in the parameter region with a relatively small decay constant, often favored in axion search experiments, special care is required when estimating the axion abundance and spectrum. We also highlight a scenario in which axions are produced through the stimulated decay of a modulus, a situation that may naturally arise in the string axiverse, where the nonlinear transition occurs across a wide parameter region. Furthermore, we discuss related phenomena, including QCD axion dark matter, the formation of axion clumps such as miniclusters and axion stars, gravitational wave production, and formation of primordial black holes as dark matter.

    hep-phastro-ph.COJHEP(2026)·8 citations
23. 23*

    Do large QCD corrections to di-Higgs decay survive parton showering? A study of $HH\to b\bar{b}\gamma \gamma$

    Jens Braun🇩🇪 · Duarte Fontes🇩🇪 · Gudrun Heinrich🇩🇪

    While significant effort has been devoted to precision calculations of the production of two Higgs bosons via gluon fusion, the treatment of their decays in this process has only recently begun to attract attention. It has been found that fixed-order QCD corrections to fiducial di-Higgs decay rates involving the $b\bar{b}$ decay channel can be substantial. Considering $HH\to b\bar{b}\gamma \gamma$, we show that such corrections arise predominantly from sensitivity to soft and collinear QCD radiation at fixed order, and that they are largely washed out once parton showers are included.

    hep-phJHEP(2025)·2 citations
24. 24*

    Axion-photon conversion in transient compact stars: Systematics, constraints, and opportunities

    Damiano F. G. Fiorillo🇩🇪 · Ángel Gil Muyor🇮🇹 · Hans-Thomas Janka🇩🇪 · Georg G. Raffelt🇩🇪 · Edoardo Vitagliano🇮🇹

    We study magnetic conversion of ultra-relativistic axion-like particles (ALPs) into photons in compact-star environments, focusing on the hot, transient conditions of core-collapse supernova (SN) remnants and neutron-star mergers (NSMs). We address previously overlooked uncertainties, particularly the suppression caused by ejected matter near the stellar surface, a region crucial to the conversion process. We derive analytical expressions for the transition rate; they reveal the influence of key parameters and their uncertainties. We update constraints using historical gamma-ray data from SN~1987A and find $g_{a\gamma }<5\times 10^{-12}{\mathrm{GeV}}^{-1}$ for $m_a\lesssim 10^{-9}$ eV. We also forecast sensitivities for a future Galactic SN and for NSMs, assuming observations with Fermi-LAT or similar gamma-ray instruments. We distinguish ALPs -- defined as coupling only to photons and produced via Primakoff scattering -- from axions, which also couple to nucleons and emerge through nuclear bremsstrahlung. We omit pionic axion production due to its large uncertainties and inconsistencies, though it could contribute comparably to bremsstrahlung under optimistic assumptions. For the compact sources, we adopt time-averaged one-zone models, guided by numerical simulations, to enable clear and reproducible parametric studies.

    hep-phastro-ph.COastro-ph.HEJCAP(2026)·37 citations
25. 25*

    Coherently enhanced decoherence and cloud substructure of atom interferometers

    Clara Murgui🇨🇭 · Ryan Plestid🇺🇸

    We study how coherent scattering of a background gas off an atom (or other matter) interferometer can lead to enhanced signals from phase shifts and contrast loss. We focus on the inclusion of realistic features of atom interferometers such as finite temperature, cloud substructure, and time-dependent cloud radii. The inclusion of these effects, extending beyond the previously considered point-like cloud approximation, naturally allow us to study the smooth transition between the coherent and incoherent scattering regimes. We discuss how the formalism presented herein can be tested in the lab (with near-infrared photons or an eV-scale electron gun), and discuss an application for the detection of dark matter interacting via long-range forces.

    hep-phphysics.atom-phquant-ph4 citations
26. 26*

    Lowering the Horizon on Dark Energy: A Late-Time Response to Early Solutions for the Hubble Tension

    Tal Adi🇺🇸

    We present a model-independent null test of the late-time cosmological response to a reduced sound horizon, as typically required by early-universe solutions to the Hubble tension. In this approach, we phenomenologically impose a shorter sound horizon without modeling early-universe physics to isolate its impact on late-time dark energy inference. Using baryon acoustic oscillations (BAO), supernovae (SN), big bang nucleosynthesis (BBN), and local $H_0$ data, while explicitly avoiding CMB anisotropies, we examine how this calibration shift propagates into constraints on the dark energy equation of state. We find that lowering $r_d$ systematically drives the $w_0$-$w_a$ posterior toward less dynamical, quintessence-like behavior, bringing it closer to $\Lambda$CDM. This result underscores that some of the apparent evidence for evolving or phantom-like dark energy may reflect early-universe assumptions rather than genuine late-time dynamics. More broadly, our analysis highlights the importance of carefully disentangling calibration effects from physical evolution in interpreting forthcoming results from DESI and future surveys.

    ↳ astro-ph.COhep-phhep-thJCAP(2026)·11 citations
27. 27*

    Search for Quintessence-Like Pseudoscalar Dark Energy Effects on ${}^{56}\text{Fe}$ Nuclear Transition Energies in Supernova 1991T

    Robert D. Orlando🇺🇸 · David S. Koltick🇺🇸 · Dennis E. Krause🇺🇸

    The nature of dark energy remains one of the most important unanswered problems in physics. Here we use gamma-ray spectra from the Type Ia supernova 1991T to constrain the recent evolution of a dynamical pseudoscalar quintessence-like field $Q(t)$. We found that the 1991T gamma rays emitted by the ${}^{56}\text{Fe}$ nuclei observed by COMPTEL aboard the Compton Gamma Ray Observatory were slightly shifted to lower energies with respect to terrestrial values, with the average fractional energy shift of both the first and second excited states found to be $\delta E/E=-0.006\pm 0.008$ including statistical and systematic errors. Assuming that this energy shift is caused by a dynamical QCD axion-like pseudoscalar field $Q(t)$, we find that observed energy deviations are consistent with a fractional rate of change of the pion mass given by $\delta \dot{m_{\pi }}/m_{\pi }=-(6\pm 9)\times 10^{-11}{\text{ yr}}^{-1}$. The observed energy deviation was also used to determine the rate of change of the quintessence-like field (${\dot{Q}}_0$) for tracking models: ${\dot{Q}}_{0,max}=(3\pm 4)\times 10^7\text{ GeV/yr}$. Our findings are consistent with the cosmological constant (${\dot{Q}}_0=0$). Furthermore, we have demonstrated how nuclear spectra produced by astrophysical events can be used to inform the nature and behavior of dark energy.

    ↳ astro-ph.COhep-phnucl-ex0 citations
28. 28*

    Comparing Minimal and Non-Minimal Quintessence Models to 2025 DESI Data

    Husam Adam🇺🇸 · Mark P. Hertzberg🇺🇸 · Daniel Jiménez-Aguilar🇺🇸 · Iman Khan🇺🇸

    In this work we examine the 2025 DESI analysis of dark energy, which suggests that dark energy is evolving in time with an increasing equation of state $w$. We explore a wide range of quintessence models, described by a potential function $V(\phi )$, including: quadratic potentials, quartic hilltops, double wells, cosine functions, Gaussians, inverse powers. We find that while some provide improvement in fitting to the data, compared to a cosmological constant, the improvement is only modest. We then consider non-minimally coupled scalars which can help fit the data by providing an effective equation of state that temporarily obeys $w<-1$ and then relaxes to $w>-1$. Since the scalar is very light, this leads to a fifth force and to time evolution in the effective gravitational strength, which are both tightly constrained by tests of gravity. For a very narrow range of carefully selected non-minimal couplings we are able to evade these bounds, but not for generic values.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2026)·23 citations
29. 29*

    How Theory-Informed Priors Affect DESI Evidence for Evolving Dark Energy

    Michael W. Toomey🇺🇸 · Gabriele Montefalcone🇺🇸 · Evan McDonough🇨🇦 · Katherine Freese🇺🇸

    Recent measurements of baryon acoustic oscillations (BAO) from the Dark Energy Spectroscopic Instrument (DESI) have been interpreted to suggest that dark energy may be evolving. In this work, we examine how prior choices affect such conclusions. Specifically, we study the biases introduced by the customary use of uniform priors on the Chevallier-Polarski-Linder (CPL) parameters, $w_0$ and $w_a$, when assessing evidence for evolving dark energy. To do so, we construct theory-informed priors on $(w_0,w_a)$ using a normalizing flow (NF), trained on two representative quintessence models, which learns the distribution of these parameters conditional on the underlying $\Lambda$CDM parameters. In the combined $\text{Planck}$ CMB + DESI BAO analysis we find that the apparent tension with a cosmological constant in the CPL framework can be reduced from $\sim 3.1\sigma$ to $\sim 1.3\sigma$ once theory-informed priors are applied, rendering the result effectively consistent with $\Lambda$CDM. For completeness, we also analyze combinations that include Type Ia supernova data, showing similar shifts toward the $\Lambda$CDM limit. Taken together, the observed sensitivity to prior choices in these analyses arises because uniform priors - often mischaracterized as "uninformative" - can actually bias inferences toward unphysical parameter regions. Consequently, our results underscore the importance of adopting physically motivated priors to ensure robust cosmological inferences, especially when evaluating new hypotheses with only marginal statistical support. Lastly, our NF-based framework achieves these results by post-processing existing MCMC chains, requiring $\approx 1$ hour of additional CPU compute time on top of the base analysis - a dramatic speedup over direct model sampling that highlights the scalability of this approach for testing diverse theoretical models.

    ↳ astro-ph.COhep-phPRD(2026)·32 citations
30. 30*

    Constraints on Dark Matter Structures around Gaia Black Holes

    Nuno P. Branco🇵🇹 · Ricardo Z. Ferreira🇵🇹 · João G. Rosa🇵🇹 · Rodrigo Vicente🇳🇱

    We demonstrate that Gaia's detection of stars on wide orbits around black holes opens a new observational window on dark matter structures -- such as scalar clouds and dark matter spikes -- predicted in a range of theoretical scenarios. Using precise radial velocity measurements of these systems, we derive state-of-the-art constraints on dark matter density profiles and particle masses in previously unexplored regions of parameter space. We also test the black hole hypothesis against the alternative of a boson star composed of light scalar fields.

    ↳ astro-ph.COhep-ph3 citations
31. 31*

    Maximal GW amplitude from bubble collisions in supercooled phase transitions

    Masaki Yamada🇯🇵

    We extend analytic formulas for the gravitational-wave (GW) spectrum from first-order phase transitions to include cosmic expansion under the thin-wall and envelope approximations. We demonstrate that even for strongly supercooled transitions the GW amplitude is bounded from above. This conclusion is explicitly verified for several representative nucleation histories, including delta-function, power-law, and power-exponential types. Moreover, the spectral shape, amplitude, and peak frequency remain largely unaffected by the details of the nucleation rate once expressed in terms of the conformal variables evaluated at an appropriately defined characteristic collision time.

    ↳ gr-qcastro-ph.COhep-phPLB(2026)·12 citations
32. 32*

    Primordial black holes in Randall-Sundrum: Cosmological signatures

    Itzi Aldecoa-Tamayo🇬🇧 · Christian T. Byrnes🇬🇧 · David Seery🇬🇧

    We reconsider primordial black hole physics in Randall-Sundrum Type-II universes, focusing on constraints from cosmological and astrophysical observables. We pay particular attention to scenarios that allow the entirety of dark matter to be in the form of higher-dimensional primordial black holes. This is possible for a range of AdS radii and black hole masses. Observable constraints are generally modified due to the changes in the higher-dimensional gravitational sector, and come from low-energy $e^{\pm }$ emission, microlensing, and possibly from contributions to unresolved radiation backgrounds. We discuss constraints from the cosmic microwave background due to injection of Hawking quanta into the intergalactic medium. Finally, we comment on recent discussions on the compatibility of higher-dimensional black holes and the KM3-230213A event.

    ↳ astro-ph.COhep-phJCAP(2026)·4 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.