Wed·Jul 30, 2025Wednesday·July 30, 2025

1. 01*

   Quantum Aspects of Natural Top Quark Condensation

   Christopher T. Hill🇺🇸

   In top quark condensation the Brout-Englert-Higgs (BEH) boson is a $\bar{t}t$ bound state. With a UV completion of a single coloron exchange interaction, a recent semiclassical treatment gave a novel theory of the BEH boson as an extended object with composite scale $M_0\sim 6$ TeV. Presently we obtain the semiclassical theory as an effective action, using the source/Legendre transformation techniques of Jackiw, \etal, and fermion loop effects in the large-$N_c$ limit by deploying an auxiliary field to implement the sum of leading fermion loop diagrams. The theory remains natural at the loop level, with fine tuning at the level of a few \%, and the effective coupling of the 4-fermion interaction, ${\bar{g}}_0^2$, is significantly enhanced by quantum loops over the fundamental coloron coupling, $g_0^2$. Hence a relatively weaker ``topcolor'' theory can produce critical coupling in the effective BEH bound state theory.

   hep-phhep-exhep-th1 citation
2. 02*

   Laser-assisted Light-by-Light Scattering in Born-Infeld and Axion-like Particle Theories

   Kai Ma🇨🇳 · Tong Li🇨🇳

   The precision measurements of well-known light-by-light reactions lead to important insights of nonlinear quantum electrodynamics (QED) vacuum polarization. The laser of an intense electromagnetic field strength provides an essential tool for exploring nonlinear QED and new physics beyond Standard Model (SM) in the high-precision frontier. In this work, we propose to search for low-energy light-by-light scattering in the collision of a photon beam and a laser pulse of classical background field. We aim to investigate the impact of Born-Infeld (BI) and axion-like particle (ALP) theories on laser-assisted light-by-light scattering. We calculate the QED light-by-light scattering cross section using complete QED helicity amplitudes, and then combine them with the amplitudes in BI or ALP theory to evaluate the total cross section. The laser-assisted SM light-by-light scattering should be observable in future experiments with very moderate integrated luminosities. The sensitivity of laser-assisted light-by-light scattering to BI and ALP parameters is presented.

   hep-phJHEP(2025)·3 citations
3. 03*

   Relativistic effects in $\text{mbox}M1$ radiative decays of heavy-light mesons

   A.E.Bondar🇷🇺 · A.I.Milstein🇷🇺

   We discuss the $\text{mbox}M1$ radiative transitions $D^{\ast }\to D\gamma$, $D_s^{\ast }\to D_s\gamma$, $B^{\ast }\to B\gamma$, and $B_s^{\ast }\to B_s\gamma$. A relativistic potential model is proposed. The corresponding Hamiltonian, when expanded to terms of the order of $v^2/c^2$, where $v$ are the quark velocities, coincides with the Breit Hamiltonian. This model allows making predictions for the widths of radiative transitions of mesons with one light quark. Taking into account relativistic effects is especially important for the transitions $D_s^{\ast +}\to D_s^{+}\gamma$ and $D^{\ast +}\to D^{+}\gamma$, where there is a large compensation in the magnitude of the magnetic moment of these mesons. Our results are consistent with known experimental data.

   hep-phhep-exPRD(2025)·3 citations
4. 04*

   Probing top-quark electroweak couplings indirectly at the Electron-Ion Collider

   Xu-Hui Jiang🇨🇳 · Yiming Liu🇨🇳 · Bin Yan🇨🇳

   Top quark electroweak interactions serve as a sensitive probe for beyond-Standard-Model physics, potentially exhibiting significant deviations from Standard Model predictions and offering crucial tests of fundamental symmetries in ultraviolet physics. This Letter investigates their measurement through deep inelastic scattering (DIS) processes involving top quark loops at the Electron-Ion Collider (EIC), within the Standard Model Effective Field Theory framework. We demonstrate that left-handed electron beam polarization can significantly enhance DIS cross sections for these interactions compared to right-handed scenario, highlighting the pivotal role of high polarization at the EIC in constraining these couplings. Compared to direct $pp\to t\bar{t}Z$ measurements at the Large Hadron Collider (LHC), DIS measurements could significantly improve these coupling constraints and effectively resolve parameter space degeneracies present in LHC data. Moreover, the expected precision from the EIC's high-luminosity phase matches that of LEP electroweak precision measurements, underscoring the EIC's significant potential to probe top quark properties.

   hep-phhep-exPRD(2025)·6 citations
5. 05*

   Thermal History of Non-equilibrated Scalars

   V. Knapp-Perez🇺🇸 · Gopolang Mohlabeng🇺🇸 · Michael Ratz🇺🇸 · Tim M.P. Tait🇺🇸

   Scalar fields in the early Universe are mostly discussed in two limits: either in equilibrium or completely decoupled. In this work we discuss scenarios where there are scalar fields that are not in equilibrium, but for which the coupling to thermal bath leads to interesting non-trivial dynamics. For example, in theories where scalar fields control the effective couplings of the theory, such out-of-equilibrium behavior can lead to cases where the couplings vary during cosmological evolution. We systematically examine the generic features governing the evolution of these couplings, and as an application we highlight a novel effect where the scalar quartic coupling of an Abelian Higgs model is modified, leading to stronger cosmological phase transitions than would be obtained for static non-evolving quartics.

   hep-phastro-ph.COhep-thJCAP(2026)·3 citations
6. 06*

   Interpreting the KM3-230213A PeV Neutrino Event via Vector Dark Matter Decay and Its Multi-Messenger Signatures

   Yu-Hang Su🇨🇳 · Si-Yu Chen🇨🇳 · Chengfeng Cai🇨🇳 · Hong-Hao Zhang🇨🇳

   The KM3NeT Collaboration recently reported the detection of an ultra-high-energy neutrino event KM3-230213A with a reconstructed energy of $220_{-110}^{+570}$ PeV, the most energetic astrophysical neutrino ever detected. The absence of convincing electromagnetic counterparts motivates exploration of exotic origins beyond standard astrophysical processes. We present a vector dark matter model based on a new $U(1{)}_X$ gauge symmetry to interpret this event through superheavy dark matter decay. Our analysis demonstrates that dark matter lifetimes in the range $7.3\times 10^{28}$ to $2.9\times 10^{30}$ s can successfully account for the KM3-230213A event while satisfying stringent constraints from gamma-ray observations. Moreover, the spontaneous breaking of $U(1{)}_X$ in our model naturally predicts cosmic string formation, generating a stochastic gravitational wave background with string tension $4.5\times 10^{-11}\lesssim G\mu \lesssim 1.2\times 10^{-10}$, consistent with recent pulsar timing array observations. This multi-messenger consistency across neutrinos, gamma-rays, and gravitational waves validates our vector dark matter interpretation of the KM3-230213A event while providing testable predictions for upcoming multi-wavelength experiments.

   hep-phastro-ph.COastro-ph.HE4 citations
7. 07*

   Decoding the role of $\rho$ mesonic states for elucidating the $e^{+}{e}^{-}\to a_2(1320)\pi$ data and other reactions

   Qin-Song Zhou🇨🇳 · Zi-Yue Bai🇨🇳 · Jun-Zhang Wang🇨🇳 · Hao Xu🇨🇳 · Xiang Liu🇨🇳

   Recently, the BESIII Collaboration observed a $\rho$-like structure $Y(2044)$ in $e^{+}{e}^{-}\to a_2(1320)\pi$, suggesting that $Y(2044)$ may be a candidate of vector meson $\rho (2D)$ by comparing resonance parameters. However, the theoretical prediction for the combined branching ratio ${\Gamma }_{e^{+}{e}^{-}}{\mathcal{B}}_{a_2(1320)\pi }$ for the pure $\rho (2D)$ state is about two orders of magnitude smaller than the experimental value. To resolve this discrepancy and decipher the nature of $Y(2044)$, this work propose an $S$-$D$ mixing scheme to reanalyze the cross section of $e^{+}{e}^{-}\to a_2(1320)\pi$, and find that the aforementioned branching ratio discrepancy can be resolved. Our results show that the $Y(2044)$ structure can be reproduced by introducing four theoretically predicted $S$-$D$ mixing $\rho$ meson states ${\rho }_{3S-2D}^{\prime }$, ${\rho }_{3S-2D}^{\prime \prime }$, ${\rho }_{4S-3D}^{\prime }$, and ${\rho }_{4S-3D}^{\prime \prime }$ as intermediate resonances, in which dominant contribution arises from ${\rho }_{3S-2D}^{\prime \prime }$ and their inference effect is also significant. Furthermore, we reanalyzed five additional isospin vector processes $e^{+}{e}^{-}\to \omega {\pi }^0$, $e^{+}{e}^{-}\to f_1(1285){\pi }^{+}{\pi }^{-}$, $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$, $e^{+}{e}^{-}\to \rho \eta$, and $e^{+}{e}^{-}\to {\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ based on the same $S$-$D$ mixing framework, and simultaneously reproduced their experimental cross section data. This work provides a unified framework to elucidate all observed $\rho$-like structures near 2 GeV in the $e^{+}{e}^{-}$ annihilation processes, and suggests that the $S$-$D$ mixing effect may be crucial for understanding the mass spectrum and decay behaviors of the higher $\rho$ meson states.

   hep-phPRD(2025)·2 citations
8. 08*

   Semiclassical analysis of axion-like particle emission via nonlinear Compton-like scattering in intense laser fields

   Pei-Lun He🇨🇳 · En-Rui Zhou🇨🇳 · Yue-Yue Chen🇨🇳

   We investigate the production of axion-like particles through nonlinear Compton-like scattering in intense laser fields using the Baier-Katkov operator method. By explicitly constructing the eikonal spinor wave function, we utilize the semiclassical nature of relativistic electrons, which simplifies the theoretical derivation and circumvents the need to evaluate certain operator products. The electron spin-resolved axion emission rate is obtained under the local constant field approximation, with explicit calculations demonstrating that transverse acceleration dominates the radiation yields. The electron spin dependence of the axion emission rate is found to differ significantly from that of photon emission by analytically examining the asymptotic behavior of the radiation in both the weak- and strong-field limits and by numerically exploring the intermediate regime. The derived spin-resolved axion emission rate can be directly incorporated into existing semiclassical Monte Carlo algorithms developed for strong-field photon processes, enabling efficient modeling of axion-like particle generation. Our results provide promising avenues for the experimental detection and control of axion-like particles with high-intensity laser facilities.

   hep-phPRD(2026)·3 citations
9. 09*

   Spin-Dependent Axion Generation with Controllable Emission Angles in Strong Laser Fields

   Jia-Ding Chen🇨🇳 · Hang Liu🇨🇳 · Kai-Hong Zhuang🇨🇳 · Baifei Shen🇨🇳 · Pei-Lun He🇨🇳 · Yue-Yue Chen🇨🇳

   We investigate axion production in the collision between a spin-polarized relativistic electron beam and an ultraintense laser pulse. A spin-resolved Monte Carlo framework is developed to model axion-electron and axion-photon couplings in arbitrary electromagnetic fields, using quantum emission probabilities under the local constant field approximation. Owing to spin-dependent asymmetries in radiation probability, the emitted axions acquire a characteristic angular deflection tied to the initial electron polarization. This spin-dependent asymmetry enables control over the axion emission direction by adjusting the polarization of the electron beam and laser field. Simulations show that a dense and collimated axion beam ($\sim 10^{10}{g}_{ae}^2$) with a tunable deflection angle ($\sim$ mrad) can be produced within tens of femtoseconds using current laser technology. Our results establish a novel mechanism for manipulating axion trajectories and open a promising route toward laboratory-based searches for the axion-electron coupling.

   hep-phPRD(2026)·5 citations
10. 10*

    One-Point energy correlator inside jets

    Zihao Mi🇨🇳 · Zhan Wang🇨🇳

    In this work, we introduce a new jet observable, the one-point energy correlators (EC), designed to characterize the in-jet energy flow distribution by measuring energy deposition at a specific angle relative to the jet axis. Building upon the transverse momentum dependent physics, we aim for the EC to provide novel insights into jet substructure and offer a new approach to study TMD physics, particularly gluon transverse momentum dependent fragmentation functions (TMDFFs) which are notoriously difficult to extract. We obtain the factorization of the EC jet function within Soft-Collinear Effective Theory and leverage the framework of semi-inclusive TMD fragmenting jet functions. We resum large global logarithms and non-global logarithms (NGLs) and show that the normalized EC jet function exhibits significantly reduced dependence on the factorization scale and is primarily sensitive to the jet scale. Finally, after incorporating non-perturbative effects, we present numerical calculations up to NNLL accuracy for global logarithms and LL accuracy for NGLs, and we compare these predictions with PYTHIA 8 simulations.

    hep-phJHEP(2025)·8 citations
11. 11*

    Hadronic Molecules and ${\chi }_{cJ}(2P)$ Coupled States

    Kotaro Miyake🇯🇵 · Yasuhiro Yamaguchi🇯🇵

    We investigate hidden-charm exotic mesons based on a coupled-channel framework, where the physical states are described as superpositions of a compact $c\bar{c}$ core (identified with the ${\chi }_{cJ}(2P)$ states) and hadronic components such as $D^{(\ast )}{\bar{D}}^{(\ast )}$. We incorporate meson exchange potentials to describe hadron-hadron interactions and determine model parameters to reproduce the observed masses of $X(3872)$ and $Z(3930)$. The model also predicts a $0^{++}$ bound state consistent with the $X(3860)$. The internal structure is found to be predominantly molecular for the $X(3872)$, while the $X(3860)$ and $Z(3930)$ have larger $c\bar{c}$ components. The coupling between $c\bar{c}$ cores and hadronic components plays a crucial role in generating these states. The resulting wave functions provide insight into the internal structure and decay properties of these exotic states.

    hep-phnucl-thPoS(2026)·0 citations
12. 12*

    Quark mass dependence of a QCD critical point and structure of the Columbia plot

    Julian Bernhardt🇩🇪 · Christian S. Fischer🇩🇪

    We study the quark-mass dependence of the QCD critical point at varying bare up/down quark masses with fixed strange quark mass. We explore the corresponding second-order critical surface in the three-dimensional Columbia plot and study the extension of the associated crossover hyperplane at real and imaginary baryon chemical potential. To this end, we employ a by now well-tested combination of lattice Yang--Mills theory and a (truncated) version of Dyson--Schwinger equations at $N_f=2+1$ quark flavours. We find evidence for a positive curvature of the second order surface at (large) real chemical potential and a crossover region for imaginary chemical potential. Our results support the notion of a tricritical point at finite chemical potential in the chiral limit.

    hep-phhep-lat4 citations
13. 13*

    One-loop Renormalization of the Type-I Seesaw Model in the Modified Minimal-subtraction Scheme

    Jihong Huang🇨🇳 · Shun Zhou🇨🇳

    Extending the Standard Model (SM) with three right-handed neutrinos, the type-I seesaw model serves as the simplest and most natural scenario to successfully explain both tiny neutrino masses and the baryon number asymmetry in the Universe. In this paper, we perform a complete one-loop renormalization of the type-I seesaw model in the modified minimal-subtraction ($\overline{\mathrm{MS}}$) scheme. The one-loop self-energy corrections of charged leptons and Majorana neutrinos are calculated in the $R_{\xi }^{}$ gauge, and the explicit expressions of all the counterterms for wave functions, fermion masses and the leptonic flavor mixing matrix are given. Furthermore, adopting the Euler-like parametrization of the $6\times 6$ unitary leptonic flavor mixing matrix, we derive one-loop renormalization-group equations for all the physical parameters in the $\overline{\mathrm{MS}}$ scheme, including neutrino masses, mixing angles and CP-violating phases. The modification of the one-loop renormalization of the original SM parameters due to the presence of heavy Majorana neutrinos is investigated as well. In this way, we provide a self-consistent theoretical framework to thoroughly test the type-I seesaw model at the one-loop level with future precision data.

    hep-phhep-exNPB(2026)·3 citations
14. 14*

    Dynamics of chiral phase transition in a $N_f=2+1$ soft-wall AdS/QCD model

    Han Tang🇨🇳 · Bin Dong🇺🇸 · Nanxiang Wen🇨🇳 · Yidian Chen🇨🇳 · Danning Li🇨🇳

    We investigate the real-time dynamics of the chiral phase transition in a soft-wall AdS/QCD model, of which the mass plane phase diagram from equilibrium calculation is qualitatively consistent with the so-called Columbia plot. By directly solving the non-equilibrium evolution of the order parameter of the chiral phase transition, i.e. the chiral condensate, we study the thermalization of the QCD matter in different regions of the quark mass plane. It is shown that, when the system is close to the transition region, the thermalization process will show non-trivial behavior in the intermediate time region.

    hep-ph1 citation
15. 15*

    Net-Charge Fluctuations in Finite Volume PNJL Model: A Probe for the QCD Critical Point

    Amal Sarkar🇮🇳 · Paramita Deb🇮🇳 · Bidhan Mandal🇮🇳 · Raghava Varma🇮🇳

    The QCD Critical Point is a pivotal feature of the phase diagram of strongly interacting matter. Signatures of the critical point are expected to manifest through the non-monotonic behavior of higher-order moments of conserved quantities, such as net-baryon ($\Delta B$), net-charge ($\Delta Q$), and net-strangeness ($\Delta S$), as a function of collision energy. These moments are connected to the thermodynamic susceptibilities, as well as to the correlation length developed in the system, which diverges at the critical point. The non-monotonic behavior of higher-order moments and their volume-independent products near the critical region supports the presence of a critical point in a finite system existing for a finite time, due to their sensitivity to critical fluctuations. These fluctuations are believed to provide key evidence in the search for the QCD Critical Point. We present the higher order moments, such as mean (M), variance $({\sigma }^2)$, skewness (S), and kurtosis $(\kappa )$ and their volume-independent moment products $(M/{\sigma }^2,s\sigma ,\kappa {\sigma }^2)$ of net-charge multiplicity distributions in the three-flavor finite volume, finite density Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model. The work has been performed at energies similar to RHIC BES energies from 7.7 GeV to 200 GeV, including 2.4 and 3 GeV in the present model. Our findings are compared with the STAR net-charge data at various collision energies to explore signals of the QCD critical point. Additionally, we contrast our results with predictions from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, the Hadron Resonance Gas (HRG) model, and available lattice QCD data. The present results offer a useful tool for extracting the freeze-out parameters in the heavy-ion collision by comparing them with the STAR net-charge result and other net-charge theoretical models.

    hep-phnucl-th4 citations
16. 16*

    Polarized-boson pairs at NLO in the SMEFT

    Ulrich Haisch🇩🇪 · Jakob Linder🇩🇪 · Giovanni Pelliccioli🇮🇹 · Emanuele Re🇮🇹 · Giulia Zanderighi🇩🇪

    We present a computation of diboson production in the $W^{\pm }Z$ channel at the Large Hadron Collider (LHC), incorporating leptonic decays of the gauge bosons and considering intermediate gauge bosons with definite polarization states. The analysis includes contributions from the Standard Model effective field theory (SMEFT) and is carried out at next-to-leading order accuracy in QCD, matched to a parton-shower simulation. Our implementation allows for the selection of specific helicity configurations, both in the Standard Model and in the presence of dimension-six operators inducing anomalous triple-gauge-boson couplings. This work provides a key ingredient for both polarization-template and quantum-tomography analyses of diboson systems at the LHC within the SMEFT framework.

    hep-phhep-exJHEP(2025)·13 citations
17. 17*

    Superradiance Constraints from GW231123

    Andrea Caputo🇨🇭 · Gabriele Franciolini🇨🇭 · Samuel J. Witte🇬🇧

    Gravitational wave observations have recently revealed with high significance, and high precision, the existence of $\mathcal{O}(100)M_{\odot }$ rapidly rotating black holes, allowing gravitational wave events to be used for the first time to probe unexplored axion parameter space using the phenomenon known as black hole superradiance. Here, we present new limits on axions using the binary black hole merger event GW231123, whose constituent black holes are among the fastest spinning observed with gravitational waves to date. We demonstrate that the most viable binary formation channels lead to conservative constraints on axion masses $\mu \sim [0.6-5]\times 10^{-13}$ eV and decay constants $f_{\Phi }\gtrsim 10^{14}$ GeV, extending existing superradiance constraints derived using x-ray observations to yet lower axion masses.

    hep-phastro-ph.COastro-ph.HEPRD(2026)·33 citations
18. 18*

    How cross section fluctuations affect multiplicity and geometry in pA collisions

    Chiara Le Roux🇸🇪

    In this paper, a new Monte Carlo Glauber model is developed for pA collisions. It uses the hadronic cross sections calculated within the KMR model as implemented in the SHRiMPS minimum bias module of the SHERPA event generator. These cross sections are obtained as functions of impact parameter and, therefore, are ready for use in a Glauber model without additional assumptions regarding their impact parameter dependence. We compare the results obtained with those from a Black Disk model and from another model with colour fluctuations. It is shown that the KMR/SHRiMPS cross sections may present very good descriptions of the multiplicity distributions in pA collisions given that they show a long tail in the distribution of wounded nucleons. Moreover, it is shown that they also increase the anisotropy in the spacial distribution of wounded nucleons, which can be important in the description of the initial states of pA collisions. The generalization to A+A collisions is straightforward.

    hep-phEPJC(2026)·0 citations
19. 19*

    Neutrino non-radiative decay in matter: constraints and prospects

    Pilar Iváñez-Ballesteros (APC, Paris)🇫🇷 · M. Cristina Volpe (APC, Paris)🇫🇷

    Neutrinos, being massive, can decay. A heavier neutrino could decay into a lighter one and a massless scalar or pseudoscalar boson, such as the Majoron. Two-body non-radiative decay could occur in dense matter, such as in the inner dense regions of a core-collapse supernova. We first derive novel bounds on neutrino-Majoron couplings using the spectral distortions induced by neutrino non-radiative two-body decay in matter, and two-dimensional likelihood analyses of the 24 ${\bar{\nu }}_e$ events from SN1987A. We then explore the prospects of neutrino-Majoron couplings from a future galactic core-collapse supernova, leaving either a neutron star or a black-hole. To this aim, we use information from detailed one-dimensional supernova simulations. We consider the supernova neutrino signal associated with inverse-beta decay in the upcoming JUNO and Hyper-Kamiokande detectors, with neutrino-argon scattering in DUNE, or with coherent neutrino-nucleus scattering in the DARWIN experiment. In a full 3$\nu$ framework, based on the spectral distortions induced by neutrino decay in matter, we perform two-dimensional likelihood analyses and provide prospects for the limits on neutrino-Majoron couplings. Our results show that the observation of a future supernova will significantly improve on the current bounds, in particular from SN1987A and neutrinoless double-beta decay. Finally, we explore the impact of neutrino decay in matter on the diffuse supernova neutrino background formed by past supernova explosions. We show for the first time that the effects on black-hole contributions are important and modify the DSNB number of events by several tens of percent in Hyper-Kamiokande.

    hep-phastro-ph.SRhep-exnucl-ex+1JCAP(2026)·4 citations
20. 20*

    Infrared singularities and the collinear limits of multi-leg scattering amplitudes

    Claude Duhr🇩🇪 · Einan Gardi🇬🇧 · Sebastian Jaskiewicz🇨🇭 · Jonas Lübken🇬🇧 · Leonardo Vernazza🇮🇹

    Scattering amplitudes are expected to admit a factorised structure in special kinematic limits, such as the Regge, soft and collinear limits. However, less is known about the precise mechanisms through which factorisation of $n$-particle scattering amplitudes is realised at high perturbative orders, where more complex structures arise. Starting with the soft anomalous dimension, in this work we investigate the multi-particle collinear limits of massless amplitudes at three- and four-loop orders. Using colour conservation and rescaling symmetry, we show how strict collinear factorisation of multiple massless final-state coloured particles is realised, and provide results for the corresponding splitting amplitude soft anomalous dimensions. In particular, we demonstrate through four loops that the conditions on the structure of the soft anomalous dimension that are required by strict collinear factorisation in all two-particle collinear limits, are sufficient to guarantee such factorisation also in any multiple collinear limit. Then, assuming that strict collinear factorisation of massless partons holds also for amplitudes containing massive coloured particles, we derive new constraints on the soft anomalous dimension from multi-collinear limits.

    hep-phhep-thJHEP(2026)·10 citations
21. 21*

    BSM: Extended Scalar Sectors

    Tania Robens🇭🇷 · Rui Santos🇵🇹

    In particle physics the world is described by a function, the Lagrangian. Each of its sectors characterizes the interactions between the particles of the Standard Model (SM). The addition of hypothetical new particles is done by including new terms in the Lagrangian. The scalar or Higgs sector of the SM is built with only one scalar complex field and it is extended by including new spin zero fields. This can help to solve questions that cannot be answered by the SM alone, like introducing dark matter candidates or new sources of CP-violation required to explain the matter-antimatter asymmetry of the universe. The corresponding theories have to be probed experimentally. For the high energy region, the standard tools are collider experiments such as the Large Hadron Collider, or other possible future facilities. Dark matter experiments scrutinize the connection between the visible and the dark world.

    hep-ph11 citations
22. 22*

    Neural network extraction of chromo-electric and chromo-magnetic gluon masses

    Jie Mei🇨🇳 · Lingxiao Wang🇯🇵 · Mei Huang🇨🇳

    We present a neural network-based quasi-particle model to separate the contributions of chromo-electric and chromo-magnetic gluons. Using dual residual networks, we extract temperature-dependent masses from SU(3) lattice thermodynamic data of pressure and trace anomaly. After incorporating physics regularizations, the trained models reproduce lattice results with high accuracy over $T/T_c\in [1,10]$, capturing both the crossover behavior near $T_c$ and linear scaling at high temperatures. The extracted masses exhibit a physically reasonable behavior: they decrease sharply around $T_c$ and increase linearly thereafter. We find significant differences between thermal and screening masses near $T_c$, reflecting non-perturbative dynamics, while they converge at $T\gtrsim 2T_c$.

    hep-ph3 citations
23. 23*

    Quantum and Material Effects in Undulator-Based LSW Searches for Dark Photons

    Wen Yin🇯🇵

    The dark photon is one of the simplest extensions of the Standard Model and provides a minimal laboratory for quantum-mechanical phenomena. Light-shining-through-a-wall (LSW) searches often adopt the dark photon-photon oscillation formula as if the sensitivity were independent of the light source, the wall, and the surrounding medium. In this paper, I revisit an LSW experiment whose light source is an undulator and systematically include various quantum effects: finite wave packets, kinematical suppression due to the microscopic structure of the source, and mixing suppression/enhancement in the wall and the air. We find that the resulting sensitivities deviate significantly from those obtained with the naïve oscillation formula, especially depending on the mass of the dark photon, relevant to reflective index of the medium or walls, there can be resonance effects enhancing the sensitivity significantly. Accounting for these effects, we show that placing a photon detector outside the shielding along the beamline of a synchrotron facility enables an economical, parasitic LSW search for dark photons.

    hep-phhep-exphysics.acc-phJHEP(2026)·3 citations
24. 24*

    Higher order electroweak radiative corrections in lepton-proton scattering using covariant approach

    Mahumm Ghaffar🇨🇦 · Aleksandrs Aleksejevs🇨🇦 · Svetlana Barkanova🇨🇦

    We perform detailed calculations of electroweak radiative corrections to parity violating lepton scattering with a proton target up to quadratic and reducible two-loop level using a covariant approach. Our numerical results are presented at energies relevant for a variety of existing and proposed experimental programs such as Qweak, P2, MOLLER, MUSE, and experiments at the EIC. Analysis shows that such corrections at the Next-to-Next-to-Leading Order (NNLO) are quite significant and have to be included in searches of physics beyond the standard model, matching the increasing precision of the future experimental programs at low-energy scales.

    hep-phhep-thPRD(2026)·0 citations
25. 25*

    Boosting VBF Reconstruction at Muon Colliders

    Carlos Henrique de Lima🇨🇦

    Forward muon detection at high-energy muon colliders is crucial for resolving the underlying electroweak process. Detecting these muons is challenging in current detector designs, limited by the shielding required to suppress the beam-induced background. This work proposes using asymmetric beam energies to boost one of the forward muons into the detector acceptance, enhancing the ability to distinguish between $W$- and $Z$-initiated vector boson fusion processes. We demonstrate the capabilities of such an asymmetric collider using VBF Higgs production at 3 and 10 TeV muon colliders with modest boost asymmetries. Asymmetric beam configurations can partially recover the physics potential lost in forward regions when detector coverage is limited.

    hep-phhep-exPRD(2026)·6 citations
26. 26*

    The goofy-symmetric Standard Model and the Hierarchy Problem

    Thede de Boer🇩🇪 · Florian Goertz🇩🇪 · Andrea Incrocci🇩🇪

    A new class of so-called "goofy" symmetries has been shown to lead to renormalization-group stable relations between parameters in two-Higgs-Doublet Models, not known before. In this work we investigate goofy transformations in the Standard Model (SM), extending them to the fermion sector. We show that the SM action is goofy "symmetric", if the Higgs mass term vanishes, while other SM interactions are allowed. Goofy symmetry could thus add another option to the very few means to successfully forbid the Higgs mass term, providing an alternative to conformal symmetry or shift symmetry. We further consider how electroweak symmetry breaking can be realized in the goofy symmetric SM via higher dimensional operators or an extended scalar sector. A viable Higgs mass can be obtained via spontaneous breaking of goofy symmetry, which can be realized via operators that would not be allowed by shift symmetry or conformal symmetry. We find that goofy-symmetric extensions of the SM are strongly constrained, but offer for example a straightforward dark matter candidate.

    hep-ph9 citations
27. 27*

    Upper Bound on Parity Breaking Scale for Doublet WIMP Dark Matter

    Matthew J. Baldwin🇺🇸 · Keisuke Harigaya🇺🇸 · Isaac R. Wang🇺🇸

    We consider weakly interacting massive particle (WIMP) dark matter in a Parity solution to the strong CP problem. The WIMP phenomenology can be drastically affected by the presence of Parity partners of the WIMP and electroweak gauge bosons. We focus on a Parity extension of $SU(2{)}_L$-doublet fermion dark matter, identify the viable parameter space, and derive the predictions of the theory. We find that the Parity symmetry breaking scale is bounded from above, with the bound given by $25-60$ TeV, depending on whether or not dark matter and its Parity partner coannihilate with each other. The High-Luminosity Large Hadron Collider, future colliders, and direct and indirect detection experiments can probe the parameter space further, with correlated signal rates.

    hep-ph4 citations
28. 28*

    New Physics in inclusive semileptonic $B$ decays

    Alexandre Carvunis🇮🇹 · Gael Finauri🇮🇹 · Paolo Gambino🇮🇹 · Martin Jung🇮🇹 · Sandro Mächler🇮🇹

    We study inclusive semileptonic $\bar{B}\to X_c\ell \bar{\nu }$ decays ($\ell =e,\mu$) in the presence of generic physics Beyond the Standard Model (BSM) that is heavy compared to the $b$-quark mass. Its effect is encoded in the Wilson coefficients of dimension-six operators of the Weak Effective Theory (WET). We compute the resulting BSM contributions to the experimentally measured kinematic moments and the total decay rate through order $\mathcal{O}({\Lambda }_{\mathrm{QCD}}^3/m_b^3)$ in the Heavy Quark Expansion, as well as the $\mathcal{O}({\alpha }_s)$ corrections for the right-handed vector current. We then perform fits to the full set of available inclusive measurements in several single-mediator scenarios and in the full WET basis. We find qualitatively new bounds in several of these scenarios, complementary to and competitive with constraints from exclusive decays.

    hep-phJHEP(2026)·10 citations
29. 29*

    Supernova cooling from neutrino-devouring dark matter

    Yugen Lin🇨🇳 · Chih-Ting Lu🇨🇳 · Ningqiang Song🇨🇳

    Supernova cooling provides a powerful probe of physics beyond the Standard Model (SM), in particular for new, light states interacting feebly with SM particles. In this Letter, we investigate for the first time the production of fermionic dark matter (DM) via the neutrino-devouring process inside a core-collapse supernova, which contributes to the excessive cooling of the supernova. By incorporating state-of-the-art supernova simulation data and the full time evolution information, we derive stringent and robust limits on DM interactions, which can improve upon direct detection limits by up to seven orders of magnitude. We exclude the cross sections down to $10^{-51}-10^{-58}$~cm${}^2$ in the keV-MeV mass range for DM-electron scattering, and $10^{-49}-10^{-56}$~cm${}^2$ in the 0.1-100~MeV mass range for DM-nucleon scattering, supplemented by complementary constraints from cosmology, astrophysics, colliders and direct detection experiments in the larger cross section regime. We also close almost the entire window in which fermionic DM constitutes $\mathcal{O}(1)$ fraction of DM for its coupling to electrons in the keV-MeV mass range.

    hep-phastro-ph.CO4 citations
30. 30*

    QCD-Gravity double copy in Regge asymptotics: from $2\to n$ amplitudes to radiation in shockwave collisions

    Himanshu Raj🇺🇸 · Raju Venugopalan🇺🇸

    These lectures discuss multi-particle production in QCD and in gravity at ultrarelativistic energies, their double copy relations, and strong parallels in emergent shockwave dynamics. Dispersive techniques are applied to derive the BFKL equation for multi-gluon production in Regge asymptotics. Identical methods apply in gravity and are captured by a gravitational Lipatov equation. The building blocks in both cases are Lipatov vertices and reggeized propagators satisfying double copy relations; in gravity, Weinberg's soft theorem is recovered as a limit of the Lipatov framework. BFKL evolution in QCD generates wee parton states of maximal occupancy characterized by an emergent semi-hard saturation scale. Renormalization group equations in the Color Glass Condensate (CGC) EFT describe wee parton correlations and their rapidity evolution. A shockwave picture of deeply inelastic scattering and hadron-hadron collisions follows, with multi-particle production described by Cutkosky's rules in strong time-dependent fields. Gluon radiation in the CGC EFT has a double copy in gravitational shockwave collisions, with a similar correspondence applicable between gluon and graviton shockwave propagators. Possible extensions of this semi-classical double copy are outlined for computing multi-particle production in gravitational shockwave collisions, self-force and tidal contributions, and classical and quantum noise in the focusing of geodesics.

    ↳ hep-thgr-qchep-phnucl-thActa Phys.Polon.B(2025)·6 citations
31. 31*

    Confronting infrared divergences in de Sitter: loops, logarithms and the stochastic formalism

    Gonzalo A. Palma🇨🇱 · Spyros Sypsas🇨🇱 · Danilo Tapia🇨🇱

    A well-established result in quantum field theory in four-dimensional de Sitter space is that the vacuum state of a massless scalar field breaks the de Sitter isometry group, leading to time-dependent (secular) growth in correlation functions computed in inflationary coordinates. This behavior is widely believed to extend to more general theories involving light scalar fields with weak non-derivative interactions. In such cases, secular growth is thought to be further amplified by loop corrections, and the stochastic formalism is often regarded as the appropriate framework to resum these infrared effects. In this article we challenge this prevailing view. A crucial distinction must be made between two cases: a massless scalar field protected by a shift symmetry, and a light scalar without such a symmetry. In the former, the shift symmetry enforces derivative interactions, yielding observables in which secular growth plays no physical role. In the latter, although correlation functions develop infrared divergences in the massless limit, they remain fully invariant under the de Sitter isometry group. We analyze the structure of these divergences arising from loop integrals and show that, in the soft-momentum limit, they do not alter the time dependence of tree-level correlators. In fact, using a de Sitter-invariant renormalization scheme based on Wilson's axioms for integration, these divergences can be systematically removed order by order. We therefore conclude that neither massless nor light scalar fields in de Sitter space exhibit genuine secular growth. We further discuss the implications of these findings for the validity and scope of the stochastic approach to inflation.

    ↳ hep-thastro-ph.COhep-ph19 citations
32. 32*

    The Non-Abelian Casimir Effect for Plates, Symmetrical Tube and Box on the Lattice

    B. A. Ngwenya🇿🇦 · A. K. Rothkopf🇰🇷 · W. A. Horowitz🇿🇦

    We present non-perturbative results of the Casimir potential in non-abelian SU(3) gauge theory in (2+1)D and (3+1)D in the confined and deconfined phase. For the first time, geometries beyond parallel plates in (3+1)D are explored and we show that the Casimir effect for the symmetrical tube and symmetrical box is attractive. The Casimir potential for the tube differs from the massless non-interacting scalar field theory prediction, where a repulsive Casimir potential is expected. Unlike the parallel plate geometry where the plate-size is fixed, in the case of the tube and box, the sizes of the faces forming the walls of the geometries changes with separation distance. We propose various methods that can be used to account for the energy contributions from creating the boundaries. We show that increasing the temperature from a confined to a deconfined phase does not alter the Casimir potential. This observation is consistent with prior work suggesting that the region inside the walls is a boundary induced deconfined phase.

    ↳ hep-lathep-phquant-phPRD(2026)·3 citations
33. 33*

    Hydrodynamics with multiple charges and holography

    Liam Gladden🇬🇧 · Victor Ivo🇺🇸 · Pavel K. Kovtun🇨🇦 · Andrei O. Starinets🇬🇧

    We establish the connection between thermodynamic and dynamical instabilities in relativistic hydrodynamics with multiple flavours of conserved U(1) charges. In theories with positive hydrodynamic entropy production, where the underlying perfect fluid has a positive speed of sound squared and satisfies the null energy condition, we show that hydrodynamic instabilities can arise only through negative diffusion coefficients associated with the U(1) charges. The onset of such instabilities is governed by the eigenvalues of the thermodynamic Hessian matrix, while the flavour-space polarisations of the unstable diffusion modes are determined by the corresponding eigenvectors. We illustrate this connection using strongly coupled N=4 supersymmetric Yang-Mills theory at finite densities of the three U(1) R-charges. In the dual holographic description, the five-dimensional STU black brane exhibits unstable quasinormal modes precisely at the onset of thermodynamic instability. We derive analytic expressions for the R-charge diffusion coefficients in several representative cases, including the configuration with three equal chemical potentials.

    ↳ hep-thgr-qchep-phnucl-thJHEP(2025)·6 citations
34. 34*

    Electrostatic toroidal bender and its fringe fields

    Rick Baartman

    I describe the COSY-Infinity code GES that we have developed and used in various forms in the past 30 years to calculate maps to third order through electrostatic bend elements. It has been a mystery that COSY's in-built procedures ES, ESP and ECL disagreed with our own code. This note is intended to clarify the issue.

    ↳ physics.acc-phhep-ph0 citations
35. 35*

    Heavy flavored hydrogen molecule systems

    Hui-Min Yang🇨🇳 · Yao Ma🇨🇳 · Shi-Lin Zhu🇨🇳

    This study provides a comprehensive analysis of $S$-wave exotic hydrogen-like three-body systems ($pp{\mu }^{-}$, $pp{\tau }^{-}$, ${\mu }^{-}{\mu }^{-}p$, ${\tau }^{-}{\tau }^{-}p$, $p{\mu }^{-}{\tau }^{-}$) with spin-parity $J^P=1/2^{+}$ and $3/2^{+}$, and four-body systems ($pp{\mu }^{-}{\mu }^{-}$, $pp{\tau }^{-}{\tau }^{-}$) with $J^P=0^{+}$, $1^{+}$, and $2^{+}$. We use complex scaling and Gaussian expansion methods to solve the complex-scaled Schrödinger equation and obtain possible bound and quasi-bound states. The resulting binding energies range from $-33.8$~keV to $-340$~eV. Notably, we present the first theoretical estimation of the bound-state energy levels of $pp{\mu }^{-}{\mu }^{-}$ and $pp{\tau }^{-}{\tau }^{-}$, which is of significant importance for understanding exotic few-body Coulomb systems. We further analyze spin configurations and root-mean-square radii to elucidate the spatial structure of these bound and quasi-bound states. Our results reveal that $K$-type spatial configurations play a crucial role in accurately describing bound and quasi-bound states in the hydrogen-molecule-like systems $pp{\mu }^{-}{\mu }^{-}$ and $pp{\tau }^{-}{\tau }^{-}$. Incorporating $K$-type configurations significantly alters the mass spectra of these states. Future muon colliders and muon facilities may offer promising platforms for the possible copious production of such heavy flavored hydrogen molecules and molecular ions. For instance, scattering processes such as $2{\mu }^{-}+{\mathrm{H}}_2\to {\mathrm{H}}_{2\mu }+2e^{-}$, ${\mu }^{-}+{\mathrm{H}}_2\to {\mathrm{H}}_{\mu \mathrm{e}}+e^{-}$, and ${\mu }^{-}+{\mathrm{H}}_2^{+}\to {\mathrm{H}}_{2\mu }^{+}+e^{-}$ could be utilized, facilitating detailed studies of intriguing states such as ${\mathrm{H}}_{2\mu }$, ${\mathrm{H}}_{\mu \mathrm{e}}$, and ${\mathrm{H}}_{2\mu }^{+}$.

    ↳ physics.atom-phhep-exhep-phnucl-thPRA(2025)·2 citations
36. 36*

    Towards a Large Physics Benchmark

    Kristian G. Barman🇧🇪 · Sascha Caron🇳🇱 · Faegheh Hasibi🇳🇱 · Eugene Shalugin🇳🇱 · Yoris Marcet🇳🇱 · Johannes Otte🇳🇱 · Henk W. de Regt🇳🇱 · Merijn Moody🇳🇱

    We introduce a benchmark framework developed by and for the scientific community to evaluate, monitor and steer large language model development in fundamental physics. Building on philosophical concepts of scientific understanding and creativity, we develop a scoring system in which each question is scored by an expert for its correctness, difficulty, and surprise. The questions are of three forms: (i) multiple-choice questions for conceptual understanding, (ii) analytical problems requiring mathematical derivation, and (iii) openended tasks requiring complex problem solving. Our current dataset contains diverse set of examples, including a machine learning challenge to classify high-energy physics events, such as the four top quark signal. To ensure continued relevance, we propose a living benchmark, where physicists contribute questions, for instance alongside new publications. We invite contributions via: http://www.physicsbenchmarks.org/. We hope that this benchmark will enable a targeted AI development that can make a meaningful contribution to fundamental physics research.

    ↳ physics.data-ancs.AIhep-phphysics.comp-ph+14 citations
37. 37*

    Chromo: A High-Performance Python Interface to Hadronic Event Generators for Collider and Cosmic-Ray Simulations

    Anatoli Fedynitch🇹🇼 · Hans Dembinski🇩🇪 · Anton Prosekin🇹🇼

    Simulations of hadronic and nuclear interactions are essential in both collider and astroparticle physics. The Chromo package provides a unified Python interface to multiple widely used hadronic event generators, including EPOS, DPMJet, Sibyll, QGSJet, and Pythia. Built on top of their original Fortran and C++ implementations, Chromo offers a zero-overhead abstraction layer suitable for use in Python scripts, Jupyter notebooks, or from the command line, while preserving the performance of direct calls to the generators. It is easy to install via precompiled binary wheels distributed through PyPI, and it integrates well with the Scientific Python ecosystem. Chromo supports event export in HepMC, ROOT, and SVG formats and provides a consistent interface for inspecting, filtering, and modifying particle collision events. This paper describes the architecture, typical use cases, and performance characteristics of Chromo and its role in contemporary astroparticle simulations, such as in the MCEq cascade solver.

    ↳ physics.comp-phastro-ph.HEhep-phComput.Phys.Commun.(2026)·1 citation
38. 38*

    Two-neutrino $\beta \beta$ decay to excited states at next-to-leading order

    Daniel Castillo🇪🇸 · Dorian Frycz🇪🇸 · Beatriz Benavente🇪🇸 · Javier Menéndez🇪🇸

    We study two-neutrino double-beta decay ($2\nu \beta \beta$) into first-excited $0_2^{+}$ states of nuclei used in $\beta \beta$ decay experiments, including ${}^{76}$Ge, ${}^{82}$Se, ${}^{130}$Te, and ${}^{136}$Xe. We calculate the corresponding nuclear matrix elements (NMEs) within the nuclear shell model, using various Hamiltonians that describe well the spectroscopy of the initial and final nuclei. We evaluate the next-to-leading order (NLO) long-range NMEs recently introduced within chiral effective field theory, keeping three terms in the expansion of the energy denominator. In most cases, NLO contributions to the half-life are below 5%, but they can significantly increase due to cancellations in the leading-order Gamow-Teller NME. A detailed analysis in terms of nuclear deformation, including triaxiality, indicates that larger deformation differences between the initial and final states generally lead to smaller NMEs, but the seniority structure of the states also plays a relevant role. The lower range of our predicted half-lives, with uncertainties dominated by the nuclear Hamiltonian used, are slightly longer than the current experimental limit in ${}^{76}$Ge and consistent with the very recent half-life indication in ${}^{82}$Se.

    ↳ nucl-thhep-exhep-phnucl-exPLB(2026)·3 citations
39. 39*

    Probing ALP-Photon Mixing with High-Resolution X-ray Spectroscopy

    Yu Zhou🇯🇵 · Jiejia Liu🇨🇳 · Volodymyr Takhistov🇯🇵 · Kazuhisa Mitsuda🇯🇵

    Axion-like particles (ALPs) provide a compelling avenue for exploring physics beyond the Standard Model. In astrophysical magnetized plasmas an ALP-photon coupling $g_{a\gamma }$ induces energy-dependent oscillations in the photon survival probability that imprint modulations on emission spectra. X-ray observations of bright spectrally-smooth sources can provide particularly sensitive probes of ultralight ALPs with masses $m_a\lesssim 10^{-11}$ eV due to long propagation distances, strong magnetic fields and high photon statistics. We present a comprehensive forecast of ALP-photon conversion in three representative systems: (i) background active galactic nuclei (AGNs) observed through foreground intracluster magnetic fields, (ii) central AGNs within their host cluster halos and (iii) Galactic X-ray binaries viewed through the Milky Way field. Using detailed simulations we assess the prospective sensitivity of high-resolution X-ray missions including XRISM, Athena, and Arcus. For typical magnetic field configurations a 5 Ms XRISM observation of the Perseus Cluster AGN NGC 1275 can reach down to $g_{a\gamma }\sim 3\times 10^{-13}$ GeV${}^{-1}$ at $m_a\lesssim 10^{-12}$ eV, while Athena's superior energy resolution improves this reach by a factor of $\sim 3$. We quantify the impact of magnetic field modeling, photon statistics, and spectral binning strategies. Our results demonstrate the scientific potential of high-resolution X-ray observations to probe photon-ALP coupling in previously inaccessible parameter space, offering a powerful window into physics beyond the Standard Model.

    ↳ astro-ph.HEastro-ph.COhep-ph0 citations
40. 40*

    One-Loop Galaxy Bispectrum: Consistent Theory, Efficient Analysis with COBRA, and Implications for Cosmological Parameters

    Thomas Bakx🇳🇱 · Mikhail M. Ivanov🇺🇸 · Oliver H. E. Philcox🇺🇸 · Zvonimir Vlah🇭🇷

    We present an efficient and accurate pipeline for the analysis of the redshift-space galaxy bispectrum multipoles at one-loop order in effective field theory (EFT). We provide a systematic theory derivation based on power counting, which features the first comprehensive treatment of stochastic EFT contributions -- these are found to significantly improve the match to data. Our computational pipeline utilizes the COBRA technique that expands the linear matter power spectrum over a basis of principal components based on a singular value decomposition, allowing the cosmology dependence to be captured to sub-permille accuracy with just eight templates. This transforms the problem of computing the one-loop EFT bispectrum to a simple tensor multiplication, reducing the computation time to around a second per cosmology with negligible loss of accuracy. Using these tools, we study the cosmological information in the bispectrum by analyzing PTChallenge simulations, whose gigantic volume provides the most powerful test of the one-loop EFT bispectrum so far. We find that the one-loop prediction provides an excellent match to the bispectrum data up to $k_{\max }=0.15h{\mathrm{Mpc}}^{-1}$, as evidenced by the precise recovery of the dark matter density ${\omega }_{\text{cdm}}$, Hubble constant $H_0$, and mass fluctuation amplitude ${\sigma }_8$ parameters, and the amplitude of equilateral primordial non-Gaussianity (PNG) $f_{\mathrm{NL}}^{\mathrm{equil}}$. Combined with the power spectrum, the COBRA-based one-loop bispectrum monopole and quadrupole yield tighter constraints than the tree-level bispectrum monopole, with the posteriors on ${\omega }_{\text{cdm}}$, $H_0$, and ${\sigma }_8$ shrinking by 44\%, 32\%, and 25\%, respectively. This suggests that the COBRA-based bispectrum analysis will be an important tool in the interpretation of data from ongoing redshift surveys such as DESI and Euclid.

    ↳ astro-ph.COhep-phhep-th23 citations
41. 41*

    Probing ALP-photon couplings in Neutron Stars: Scalar versus pseudoscalar cases

    D. Suárez-Fontanella🇪🇸 · C. Albertus🇪🇸 · M. Ángeles Pérez-García🇪🇸

    We investigate the distribution of an interacting axion-like massive field within a magnetized Neutron Star. For this we consider the effect of an intense density-dependent axially symmetric stellar magnetic field $\mathbf{B}(r,\theta )$ adding another much weaker, but non-vanishing, electric field. We particularize the latter for the case when a finite chiral charge density is present. The axion field is thus coupled to a generic function $Q(F_0,G_0)$ depending on Lorentz invariants $F_0,G_0$ which can be constructed from these electromagnetic fields. From this, the static axion field equations are solved as function of stellar radial coordinate and angular direction, $a(r,\theta )$, using a prescribed linear form for $Q$. In addition, we use a semi-analytical approach to calculate the stellar structure in this hybrid system where pressure components are treated under a perturbative scheme, provided induced deformations with respect to spherical symmetry are tiny. Our results show that the axion couplings to magnetic and electric fields along with its mass, critically determine the axion spatial distribution. Furthermore, we focus on the possibility that the axion field might accumulate in specific outer regions of the star, particularly within the crust, where it could form a condensate. We explore the possible presence of magnetic flux tubes from superconductor phases in this outer layers and qualitatively show they may enhance local conversion into photons. We explore prospects of detectability through indirect methods.

    ↳ astro-ph.HEastro-ph.COastro-ph.SRhep-phPRD(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.