Thu·Aug 14, 2025Thursday·August 14, 2025

1. 01*

   Charge dependence of mesons with flavored contact-interaction couplings

   Fábio L. Braghin🇧🇷 · Bruno El-Bennich🇧🇷 · Fernando E. Serna🇨🇴

   Effective interaction models of quantum chromodynamics, based on quark degrees of freedom, have been successfully employed to compute the properties of a large array of ground and excited meson and baryon states, along with their electromagnetic form factors, distribution functions and thermal behavior. Amongst them, the contact-interaction model, while non-renormalizable, implements confinement, satisfies Lorentz covariance and correctly describes chiral symmetry and its dynamical breaking pattern. Original studies focused on the light hadron sector in the isospin limit and were thereafter extended to heavy mesons and baryons. The strong effective couplings, as well as infrared and ultraviolet regulators, are flavor-dependent model parameters adjusted to reproduce hadronic observables. In contrast, in this study we combine SU(4) flavor-symmetry breaking couplings, obtained from one-loop vacuum polarization amplitudes in the presence of background constituent quark currents, with the contact-interaction model. This allows us to reduce the number of mass-dimensioned parameters and to consistently relate all flavored couplings to a single mass scale, while the masses and weak decay constants of the pions, kaons, $D$ and $D_s$ mesons are in good agreement with average reference values. Allowing for realistic isospin breaking, $m_d/m_u=1.7$, in conjunction with the effect of the flavored couplings, leads to a mass splitting, $m_{{\pi }^{+}}-m_{{\pi }^0}\approx 0.3$ MeV, that agrees with lattice QCD values. For the kaons, the mass difference is $m_{K^0}-m_{K^{\pm }}\approx 2.3$ MeV, whereas $m_{D^{\pm }}-m_{D^0}\approx 0.5$ MeV and the ${\eta }_c$ is 6\% lighter than the experimental mass.

   hep-phhep-latnucl-thPRD(2026)·1 citation
2. 02*

   Control of nonlinear Compton scattering in a squeezed vacuum

   A. Di Piazza🇺🇸 · K. Qu🇺🇸

   Electromagnetic radiation by accelerated charges is a fundamental process in physics. Here, we introduce a quantum-optical framework for controlling the emission of radiation of an electron in an intense laser field via squeezed vacuum states. By engineering the quantum fluctuations of the emission modes, we demonstrate that the probability of nonlinear Compton scattering can be significantly enhanced or suppressed through tunable squeezing amplitude and angle. We show numerically that our predictions are experimentally accessible with current squeezing technologies, establishing a new paradigm for quantum control in high-intensity light-matter interactions.

   hep-phquant-phPRL(2026)·6 citations
3. 03*

   Effects of CPT violation on the neutrino charge radius in the Standard Model Extension

   Y. Flores-Orea🇲🇽 · J. J. Toscano🇲🇽

   CPT-odd effects on the neutrino charge radius are studied within the Standard Model Extension. We consider CPT violation from the electroweak Yang-Mills sector, characterized by Lorentz-violating coefficients $(k_1{)}_{\mu }$ and $(k_2{)}_{\mu }$, which have positive mass units. The $\bar{\nu }\nu \gamma$ vertex arises at tree level via exchange of two $Z$ bosons. Although suppressed by $\frac{1}{m_Z^4}$, this process is notable. The vertex function ${\Gamma }_{\mu }$ includes three independent gauge structures satisfying the Ward identity $q^{\mu }{\Gamma }_{\mu }=0$, characteristic of neutral particles, and induces gauge-independent electromagnetic form factors. Besides charge and anapole, two novel form factors appear. The charge form factor $f_Q(q^2)$ contains an energy-dependent term causing $f_Q(0)\ne 0$, so electromagnetic properties are undefined for real photons with CPT violation. Instead, $f_Q$ and the charge radius are defined in the static limit: $q^0=0$ and $\mathbf{q}\to 0$. Here, $f_Q(0,0)=0$ and a correction to the SM neutrino charge radius is found: \[ \langle r^2_\nu \rangle_{CPTV} = \frac{3c_{2W}}{2c_W^4} \left[\frac{k_2^2}{m_Z^2} + \frac{\mathbf{k}_2^2}{m_Z^2}\cos^2\theta_\gamma \right] \frac{1}{m_Z^2}, \] with ${\theta }_{\gamma }$ the angle between $\mathbf{q}$ and ${\mathbf{k}}_2$. Using recent bounds on $(k_i{)}_{\mu }$ and reasonable assumptions, we obtain a small correction $⟨r_{\nu }^2{⟩}_{CPTV}\le 0.83\times 10^{-51}{\mathrm{cm}}^2$.

   hep-phInt.J.Mod.Phys.A(2025)·1 citation
4. 04*

   Spinless glueballs in generalized linear sigma model

   Amir H. Fariborz🇺🇸

   Within the framework of the generalized linear sigma model, a comprehensive analysis of scalar and pseudoscalar glueballs and their mixing with mesons is presented. The Lagrangian of the model contains two chiral nonets, a quark-antiquark type and a two-quark two-antiquark type. The pseudoscalar and scalar glueballs are introduced through their connections with the axial and the trace anomalies of QCD, respectively. It is found that in order to satisfy the axial anomaly and at the same time accurately generate all seven eta masses, it is necessary to include at least two pseudoscalar glueballs, a physical one and an unphysical one that gets integrated out and yields an effective instanton-type term which is needed in generation of the eta masses. At the leading order, which corresponds to keeping effective terms in the Lagrangian that contain no more than eight underlying quarks and antiquarks, the mass spectrum of the model is worked out and shown to be in complete agreement with experiment. The quark and glue contents of the isosinglet scalars below 2 GeV, and of the isosinglet pseudoscalars up to around 2.2 GeV, are analyzed in detail and their correlations with the scalar glueball condensate are examined. Decay widths of isosinglet scalars as well as different self consistencies within this framework are used to probe the glueball condensate and thereby estimate the quark and glue contents of these states. In the pseudoscalar sector, the state that is dominantly made of glue is clearly a state with mass above 2 GeV. In the scalar sector, the identification of glue contents is less certain and in principle the three isosinglets in the 1.5-2.0 GeV can contain substantial glue. These glue contents are determined as functions of the scalar glueball condensate which is the key quantity in this analysis.

   hep-phhep-exhep-latnucl-thPRD(2025)·0 citations
5. 05*

   Unitarization of the Sommerfeld enhancement through the renormalization group

   Yuki Watanabe🇯🇵

   When a pair of dark matter particles interacts via a long-range force mediated by a light particle, their nonrelativistic annihilation cross section can be significantly enhanced - a phenomenon known as the Sommerfeld enhancement. This enhancement exhibits resonant behavior if the long-range potential supports shallow bound states or narrow resonances, which can lead to violations of the partial-wave unitarity bound. We identify the origin of this pathological behavior as the emergence of secular terms in perturbative expansions associated with low-energy composite states of the long-range potential. To address this issue, we propose a renormalization group improvement of the perturbative series. The resulting improved amplitude provides a unitarity-consistent form of the Sommerfeld enhancement, with its poles acquiring an imaginary part that reflects the decay width of the annihilating bound states. We also briefly discuss the implications of our approach from the perspective of Wilsonian renormalization group, and comment on its potential application to higher-order annihilation processes such as bound-state formation.

   hep-phJHEP(2026)·5 citations
6. 06*

   The virtual contributions from $K^{\ast }$ in the $B\to K^{\ast }\pi h$ and $B\to K\rho h$ decays

   Ai-Jun Ma🇨🇳 · Wen-Fei Wang🇨🇳

   Inspired by the significant virtual contributions of the subprocesses $D^{\ast }/B^{\ast }\to D\pi$ and $\rho \to \omega \pi /K\bar{K}$ in the three-body hadronic $B$ meson decays, we study the off-shell effects of the resonance $K^{\ast }$ decaying into the $K^{\ast }\pi$ or $K\rho$ system in the decays $B\to K^{\ast }\pi h$ and $B\to K\rho h$ (with $h=\pi ,K$) within the perturbative QCD approach. The strong coupling constants $g_{K^{\ast }{K}^{\ast }\pi }$ and $g_{K^{\ast }K\rho }$ involved in this work are derived from the coupling constant $g_{\rho \omega \pi }$ under the flavor SU$(3)$ symmetry. The $CP$ averaged branching fractions for the quasi-two-body decays $B\to K^{\ast }[\to K^{\ast }\pi ]h$ and $B\to K^{\ast }[\to K\rho ]h$ are predicted to be on the order of $10^{-9}$ to $10^{-7}$ in this study. And the branching fractions for the decays $B\to K^{\ast }[\to K\rho ]h$ are found to be around half of the corresponding results for the $B\to K^{\ast }[\to K^{\ast }\pi ]h$ channels, mainly due to the phase space difference between the $K\rho$ and $K^{\ast }\pi$ pairs originating from the intermediate state $K^{\ast }$. Experimental data for the $K^{\ast }$ decaying into the final states $K^{\ast }\pi$ and $K\rho$ in the $B$ meson decays is expected to be obtained by the LHCb and Belle-II experiments in the near future.

   hep-phPRD(2025)·2 citations
7. 07*

   Neutrino Mass Predictions with an AI-based Algorithm under $A_4$ Modular Symmetry

   Muhammad Waheed Aslam🇵🇰 · Abrar Ahmad Zafar🇵🇰 · Muhammad Naeem Aslam🇵🇰

   This research undertakes a comprehensive exploration of neutrino mass model grounded in $A_4$ discrete non-Abelian modular symmetry formulated within a linear seesaw framework that modifies the conventional type-I seesaw structure with a focus on optimizing the model parameters using incomprehensible but intelligible-in-time logics optimization algorithm (ILA), an AI-based algorithm. In contrast to traditional discrete flavor symmetry frameworks, modular symmetry significantly reduces the number and complexity of flavon fields needed to generate realistic fermion mass textures. The key predictions include neutrino masses, $U_{PMNS}$ matrices, effective neutrino masses for neutrinoless double beta decay, beta decay, Dirac and Majorana CP violation phases for normal (NO) and inverted mass ordering (IO), offering testable implications. The working efficiency of the ILA optimization technique is also estimated. The optimized neutrino oscillation parameters are well consistent with recent experimental data. Our analysis also aligns with Planck cosmological constraints on the sum of neutrino masses $0.06<\Sigma m<0.12$.

   hep-ph0 citations
8. 08*

   $U$-spin sum rules for two-body decays of bottom baryons

   Si-Jia Wen🇨🇳 · Wei-Chen Fu🇨🇳 · Di Wang🇨🇳

   $U$-spin symmetry, which reflects the symmetry between the down-type $d$ and $s$ quarks, is a powerful tool for analyzing heavy hadron weak decays. Motivated by recent experimental achievements in the bottom baryon sector, we study the $U$-spin sum rules for bottom baryon decays. The effective Hamiltonian for $b$ quark decay is zero under the $U$-spin lowering operators $U_{-}^n$, permitting us to derive $U$-spin sum rules involving only the $b\to d$ transition or $b\to s$ transition. Moreover, a new operator, $S_b=U_{+}+r{U}_3-r^2{U}_{-}$, is proposed to generate $U$-spin sum rules involving both the $b\to d$ and $b\to s$ transitions. The proof that the effective Hamiltonian for $b$ quark decay is zero under $U_{-}^n$ and $S_b$ is presented. The master formulas for generating $U$-spin sum rules for the two-body decays of bottom baryons involving $b\to c\overline{c}d/s$, $b\to c\overline{u}d/s$, $b\to u\overline{u}d/s$, and $b\to u\overline{c}d/s$ transitions are derived. Numerous $U$-spin sum rules for the two-body decays of bottom baryons are obtained through these master formulas, which provide hints for new decay modes and enable the extraction of dynamical information. As a phenomenological analysis, some branching fractions are predicted according to $U$-spin symmetry. Several rate and decay parameter sum rules beyond the $U$-spin limit are found, providing a more precise test of flavor symmetry in the bottom baryon sector. Moreover, some $CP$ asymmetry relations for $U$-spin conjugate pairs in heavy baryon decays are derived for the first time by taking partial-wave amplitudes into account.

   hep-phEPJC(2026)·4 citations
9. 09*

   Gravitational Wave Signatures of $\mathrm{U}(1{)}_{\mathrm{X}}$ Breaking and Right-Handed Neutrino Dynamics

   Arnab Chaudhuri🇯🇵 · Priya Mishra🇮🇳 · Rukmani Mohanta🇮🇳

   The Standard Model (SM) leaves several fundamental questions unanswered, including the origin of neutrino masses, the baryon asymmetry of the Universe, and the nature of dark matter. Motivated by these gaps, we investigate an extension of the SM with an additional local $U(1{)}_X$ gauge symmetry and a complex scalar singlet that spontaneously breaks this symmetry via its vacuum expectation value. The extended framework naturally accommodates three right-handed neutrinos (RHNs) to ensure anomaly cancellation and implements a type-I seesaw mechanism for active neutrino masses. We utilized Casas-Ibarra parameterization to systematically reconstruct the Yukawa coupling matrix which automatically satisfy the observed neutrino data. Furthermore, we estimate the key parameters of the first-order phase transition and compute the resulting stochastic gravitational wave spectrum, demonstrating that it can lie within the reach of forthcoming experiments such as LISA, DECIGO, BBO, and the Einstein Telescope. The right-handed neutrinos also open a viable path for thermal leptogenesis, providing a unified link between neutrino mass generation, baryogenesis, and gravitational wave signatures. Our results demonstrate that this minimal $U(1{)}_X$ scenario remains a promising probe for physics beyond the Standard Model, accessible through upcoming gravitational wave and neutrino experiments.

   hep-phastro-ph.COJCAP(2026)·5 citations
10. 10*

    Multipolar transitions excited by twisted photons in heavy quarkonia

    P.S. Korolev🇷🇺 · V.A. Ryakin🇷🇺

    In this study, we investigate the excitation of multipole transitions in quarkonium systems by high-energy photons carrying orbital angular momentum. We derive explicit expressions for the amplitude and probability of photoexcitation incorporating the dynamics of the quarkonium center of mass. It is shown that the leading contribution to the transitions induced by twisted photons comes from the multipole $j=|m_{\gamma }|$ and $m_{\gamma }=l^{\prime }-l$ in the long-wave approximation. Despite the fact that similar transitions can be excited by plane-wave photons, twisted photons with $|m_{\gamma }|>1$ enable the isolation of higher multipoles offering a unique spectroscopic tool. The fulfillment of the derived selection rules imposes constraints on the parameters of the wave packet of the quarkonium center of mass, since, in general, the angular momentum can be transferred to the center of mass. As a case study, we examine the octupole transition $1^3{G}_3\to 3^3{P}_0$ in the charmonium system. We also compare the probabilities of excitation of this multipole transition by plane-wave and twisted photons with different polarizations.

    hep-phnucl-thEPJC(2026)·1 citation
11. 11*

    $gg\to ZH$ : updated predictions at NLO QCD

    Benjamin Campillo Aveleira🇩🇪 · Long Chen🇨🇳 · Joshua Davies🇬🇧 · Giuseppe Degrassi🇮🇹 · Pier Paolo Giardino🇪🇸 · Ramona Gröber🇮🇹 · Gudrun Heinrich🇩🇪 · Stephen Jones🇬🇧 · Matthias Kerner🇩🇪 · Johannes Schlenk🇨🇭 · Matthias Steinhauser🇩🇪 · Marco Vitti🇩🇪

    We present state-of-the-art predictions for the inclusive cross section of gluon-initiated $ZH$ production, following the recommendations of the LHC Higgs Working Group. In particular, we include NLO QCD corrections, where the virtual corrections are obtained from the combination of a forward expansion and a high-energy expansion, and the real corrections are exact. The expanded results for the virtual corrections are compared in detail to full numerical results. The updated predictions show a reduction of the scale uncertainties to the level of 15%, and they include an estimate of the top-mass-scheme uncertainty.

    hep-phhep-exSciPost Phys.Comm.Rep.(2026)·7 citations
12. 12*

    Data-driven analyses and model-independent fits for present $b\to s\ell \ell$ results

    T. Hurth🇩🇪 · F. Mahmoudi🇫🇷 · Y. Monceaux🇫🇷 · S. Neshatpour🇫🇷

    We present a critical assessment of the present $B$ anomalies in the exclusive $b\to s\ell \ell$ mode based on the QCD factorisation (QCDf) approach. In particular, we analyse the impact of different local form factor calculations and of the largest bin in the low-$q^2$ region. We also present a model-independent analysis of the new results of the LHCb and CMS experiments on the $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ angular observables. In addition, we update the global fit by including all $b\to s$ observables incorporating the new data from CMS and LHCb. In these analyses, we use 10% or higher guesstimates of the non-factorisable power corrections as additional uncertainties, serving as a placeholder for robust estimates of these contributions. Updating earlier results, we also analyse the combined LHCb and CMS data on the $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ angular observables using data-driven approaches to find indications whether these tensions between the QCDf predictions and the present data are due to underestimated subleading hadronic contributions or due to new physics effects.

    hep-phPRD(2025)·21 citations
13. 13*

    Bubble Trouble: a Review on Electroweak Baryogenesis

    Jorinde van de Vis🇨🇭 · Jordy de Vries🇳🇱 · Marieke Postma🇳🇱

    The origin of the universal asymmetry between matter and antimatter remains a mystery. Electroweak baryogenesis is a well-motivated mechanism for generating the asymmetry dynamically, using interesting features of the Standard Model. In addition, it relies on beyond-the-Standard Model physics active around the electroweak scale: new physics coupling to the Higgs to make the electroweak phase transition first order, and a new mechanism of CP violation. The relatively low energy scale at which electroweak baryogenesis occurs makes certain aspects of the mechanism testable through collider experiments, electric dipole moment measurements, and gravitational wave observations. However, scenarios of electroweak baryogenesis are increasingly challenged by results from contemporary experiments. The developing experimental programs will play a crucial role in either falsifying or detecting the new physics responsible for electroweak baryogenesis. To achieve this, it is essential to make precise predictions for the baryon asymmetry and the corresponding experimental signatures within specific scenarios. This review aims to provide a comprehensive overview of the rich physics involved in these predictions. Our goal is to offer a practical computational guide, with a focus on recent developments in the field.

    hep-phastro-ph.COhep-exPPNP(2026)·33 citations
14. 14*

    Can the Odderon be "Supercritical"?

    Vladimir A. Petrov🇷🇺

    Based on the postulate that a $C$-odd exchange leads to repulsion in the particle-particle system (say, $pp$) and to attraction in the antiparticle-particle system (say, $\bar{p}p$), we show that the Odderon intercept cannot be greater than unity.

    hep-ph1 citation
15. 15*

    Baryon-baryon, meson-meson, and meson-baryon interactions in nonrelativistic QCD

    Benoît Assi🇺🇸 · Anthony Grebe🇺🇸 · Michael Wagman🇺🇸

    Van der Waals potentials describing interactions between color-singlet mesons and/or baryons vanish at leading order in potential nonrelativistic quantum chromodynamics (pNRQCD). This result and constraints from Gauss's law are used to prove that weakly-coupled pNRQCD van der Waals potentials in generic non-Abelian gauge theories with only heavy quarks are too weak to form bound states whose color state is a product of color-singlets. Quantum Monte Carlo calculations of four, five, and six quarks with equal masses provide numerical evidence that exotic color configurations are higher energy than products of color-singlet hadrons, suggesting that equal-mass fully-heavy tetraquark, pentaquark, and hexaquark bound states do not exist at next-to-leading order in pNRQCD and at all orders in QCD-like theories in which all quark masses are asymptotically large. Mechanisms for generating hadron-hadron bound states are identified, which necessarily involve large quark-mass hierarchies, relativistic effects arising from the presence of sufficiently light quarks, or nonperturbative effects outside the scope of weakly-coupled pNRQCD.

    hep-phhep-lathep-thnucl-thPRD(2026)·3 citations
16. 16*

    Prediction for Maximum Supercooling in SU(N) Confinement Transition

    Prateek Agrawal🇬🇧 · Gaurang Ramakant Kane🇬🇧 · Vazha Loladze🇬🇧 · John March-Russell🇬🇧

    The thermal confinement phase transition (PT) in $SU(N)$ Yang-Mills theory is first-order for $N\ge 3$, with bounce action scaling as $N^2$. Remarkably, lattice data for the action include a small coefficient whose presence likely strongly alters the PT dynamics. We give evidence, utilizing insights from softly-broken SUSY YM models, that the small coefficient originates from a deconfined phase instability just below the critical temperature. We predict the maximum achievable supercooling in $SU(N)$ theories to be a few percent, which can be tested on the lattice. We briefly discuss the potentially significant suppression of the associated cosmological gravitational wave signals.

    hep-phhep-lathep-thPRL(2026)·10 citations
17. 17*

    Spectral function approach in NuWro: modeling of multinucleon final states in quasielastic scattering

    Artur M. Ankowski🇵🇱 · Rwik Dharmapal Banerjee🇵🇱 · Jan T. Sobczyk🇵🇱 · José L. Bonilla🇵🇱 · Krzysztof M. Graczyk🇵🇱 · Beata E. Kowal🇵🇱 · Hemant Prasad🇵🇱

    Neutrino-oscillation experiments performed in the few-GeV energy region create an urgent demand for a significant improvement in the accuracy of modeling of neutrino interactions with atomic nuclei. Here, we report an updated implementation of the spectral function approach in the \nuwro{} Monte Carlo generator, which consistently treats multinucleon final-states in quasielastic scattering at the inclusive and exclusive level. After validating its accuracy against inclusive electron-scattering data, we compare its predictions to various neutrino cross sections from MicroBooNE. We find that with the multinucleon contribution, these data are reproduced with ${\chi }^2$ per degree of freedom of 1.3--1.8, compared to 2.7--7.2 without it.

    hep-phnucl-exnucl-th4 citations
18. 18*

    Extended Color Twin Higgs

    Brian Batell🇺🇸 · Thomas Cochran🇺🇸 · Logan Page🇺🇸 · Christopher B. Verhaaren🇺🇸

    We describe a novel variation of the mirror Twin Higgs model in which the color gauge group in both sectors is extended to SU(4${)}_c$ and spontaneously broken to SU(3${)}_c$ exclusively in the visible sector. Through this process, the mirror $Z_2$ symmetry is spontaneously broken, allowing for a phenomenologically viable electroweak vacuum alignment. This structure produces interesting collider signatures, including heavy vectors and fermions with fractional electric charges. The twin sector, with unbroken SU(4${)}_c$, produces interesting cosmological characteristics, such as the possibility to reduce $\Delta N_{\text{eff}}$ and stable spin-0 baryons. The enlarged top quark sector required by the extended color gauge symmetry preserves naturalness, with even less tuning than the original twin Higgs in many circumstances.

    hep-phJHEP(2025)·1 citation
19. 19*

    Leptogenesis and neutrino mass with one right-handed neutrino and Higgs inflaton

    Disha Bandyopadhyay🇮🇳 · Debasish Borah🇮🇳 · Suruj Jyoti Das🇰🇷 · Nobuchika Okada🇺🇸

    We propose a novel and minimal setup where the observed baryon asymmetry of the Universe and neutrino oscillation data can be satisfied with only one right-handed neutrino (RHN) and a second Higgs doublet with the latter being also responsible for driving cosmic inflation. While inflation is realised via non-minimal coupling of the Higgs to gravity, baryon asymmetry is generated via Affleck-Dine leptogenesis. Due to the presence of only two new fields beyond the standard model (BSM), the proposed setup remains very predictive with only a small allowed parameter space consistent with the PLANCK 2018 and ACT 2025 data simultaneously. The preferred mass spectrum of the BSM particles also keeps the detection prospects alive at terrestrial experiments.

    hep-phastro-ph.COPRD(2026)·0 citations
20. 20*

    The Quark Structure of the Nucleon and Moat Regimes in Nuclear Matter

    Theo F. Motta🇧🇷 · Gastão Krein🇧🇷

    We employ a model of nuclear structure that takes into account the quark substructure of the baryons to understand the behavior of static two-point correlation functions of meson fields in dense nuclear matter. We show that these correlation functions display ``moat'' regimes, where the inverse static correlation function is nonmonotonic in momentum space. This can have interesting consequences for the nature of nuclear matter, and it strengthens the possibility of a liquid-crystal phase for high densities.

    ↳ nucl-thhep-phPRD(2025)·4 citations
21. 21*

    Exact expressions for nonperturbative guiding center theory in symmetric fields

    I. Hollas🇺🇸 · R. Agarwal🇺🇸 · J. W. Burby🇺🇸 · A. J. Brizard🇺🇸

    We apply a recently-developed nonperturbative guiding center formalism to charged particle dynamics in fields with two-parameter continuous symmetry groups. This entails finding exact constants of motion, valid in the nonperturbative regime, that agree with Kruskal's adiabatic invariant series to all orders in the perturbative regime, when the field scale length is large compared with a typical gyroradius. We demonstrate that the nonperturbative guiding center model makes exact predictions in these cases, even though it eliminates the cyclotron timescale, thereby establishing a theoretical baseline for performance of the nonperturbative formalism.

    ↳ physics.plasm-phhep-ph0 citations
22. 22*

    Linear Polarization in a Black Hole, 4U~1957+115 and its X-ray Spectral Analysis

    Lev Titarchuk🇮🇹 · Elena Seifina🇷🇺 · Paolo Soffiitta🇮🇹 · Diana Makhinya🇷🇺

    We present a new spectro-polarimetric method for estimation of the inclination of X-ray binaries using the linear polarization (LP) value in black hole (BH) sources, based on the early paper by Sunyaev \& Titarchuk (1985, ST85). The X-ray LP arises from multiple scattering of initially soft photons in a hot, optically thick Compton cloud (CC) using a flat geometry. ST85 showed that the LP degree $P$ depends on the binary inclination $i$ and remains independent of the photon energy. Moreover, the $P$ follows a characteristic angular distribution based on the CC optical depth ${\tau }_0$, in particular for ${\tau }_0>$ 10 the LP follows the Chandrasekhar (1950) distribution. In light of the vast number of recent IXPE spectro-polarimetric observations of BHs, testing this approach in combination with spectral analysis of these sources by other missions is desirable. In particular, the BH source, 4U 1957+115 was observed with IXPE in the high/soft state for which $P\sim 2\%$ was found (Marra et al. 2024). To apply the new method, in addition to knowing $P$ for a given source, it is necessary to estimate the CC optical depth ${\tau }_0$ and then to calculate of the best-fit photon index $\Gamma$ and the plasma temperature $k{T}_e$. We present the X-ray spectral analysis of 4U~1957+11 using data from IXPE, NuSTAR, NICER, RXTE}, Swift, Suzaku and ASCA. We show that the X-ray source spectra are well described by the Comptonization model with $\Gamma$ varying from 1.5 to 3. We find a monotonic increase in $\Gamma$ with the mass accretion rate, $\dot{M}$, and a final saturation of the index at $\Gamma \sim 3$ for high $\dot{M}$. We determine a BH mass by the scaling method: $M_{1957}=4.8\pm 1.8M_{\odot }$, assuming a source distance of 22 kpc, using H 1743-322, 4U 1630-47, and GRS 1915+105 as reference sources.

    ↳ astro-ph.HEhep-phApJ(2025)·0 citations
23. 23*

    Thermodynamics of fermionic excitations in heavy-quark QCD

    Kei Tohme🇯🇵 · Takahiro M. Doi🇯🇵 · Masakiyo Kitazawa🇯🇵 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    We investigate the thermodynamic properties of fermionic excitations in heavy-quark QCD on the lattice with Wilson fermions. The grand potential is calculated analytically in the hopping parameter expansion (HPE) on the basis of the cumulant expansion. Using the grand potential, we compute the quark number susceptibilities and their ratios up to next-to-leading order in the HPE. The ratio of fourth- to second-order susceptibilities is shown to be unity (nine) in the deconfined (confined) phase at the leading order. Excitation properties of baryonic and quark modes in each phase are also investigated utilizing the Boltzmann statistics. We obtain an analytic formula for the quark excitation energy in the deconfined phase, while that for baryonic excitations in the confined phase is decomposed into flavor multiplets.

    ↳ hep-lathep-phhep-thnucl-thPRD(2025)·4 citations
24. 24*

    Fundamental Physics with Pulsars around Sagittarius A${}^{\star }$

    Lijing Shao🇨🇳 · Zexin Hu🇨🇳

    Searching for radio pulsars orbiting around the Galactic centre black hole (BH), Sagittarius A${}^{\star }$ (Sgr A${}^{\star }$), represents a holy grail goal for large-area radio telescopes, in particular for the Square Kilometre Array. Follow-up timing observation of such a PSR-Sgr A${}^{\star }$ binary system with an orbital period $\lesssim O(1\mathrm{year})$ will bring forward a handful of new tests on different aspects of fundamental physics that are barely accessible with other means. However, mass perturbation in the Galactic centre harms the gravitational cleanness of PSR-Sgr A${}^{\star }$ systems. In order to flexibly account for perturbations, a numerical pulsar timing model is gradually being built, which can be used to probe the spacetime around Sgr A${}^{\star }$ BH and study the nature of dark matter.

    ↳ astro-ph.HEgr-qchep-phJ.Phys.Conf.Ser.(2026)·5 citations
25. 25*

    Primordial Black Hole Formation and Spin in Matter Domination Revisited

    Weitao Ye🇨🇳 · Yungui Gong🇨🇳 · Tomohiro Harada🇯🇵 · Zhaofeng Kang🇨🇳 · Kazunori Kohri🇯🇵 · Daiki Saito🇰🇷 · Chul-Moon Yoo🇯🇵

    In this article, we calculate the mass distribution of primordial black holes (PBHs) formed in the matter-dominated (MD) era by the peak theory. We apply the Zel'dovich approximation to track the nonlinear evolution of overdensities and compute the PBH abundance and mass function by incorporating a PBH formation criterion based on the hoop conjecture. We find that the PBH abundance $\beta$ follows the scaling law $\beta \simeq A_{\gamma }{\sigma }_h^{\ast 5}$ for ${\sigma }_h^{\ast }\ll 1$. Here, ${\sigma }_h^{\ast }$ is the quantity that characterizes the variance of the density fluctuation at the horizon entry. We also find that, in contrast to the previous estimates, the PBH spin is very small for ${\sigma }_h^{\ast }\ll 1$ but could be larger for larger ${\sigma }_h^{\ast }$ and broader power spectra. Finally, specializing to a monochromatic power spectrum, we prove analytically that the PBH mass distribution becomes effectively monochromatic and reveal that the resultant PBH abundance is approximately 19 times the previous prediction.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2025)·17 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.