Fri·Sep 26, 2025Friday·September 26, 2025

1. 01*

   Z-boson quantum tomography at next-to-leading order

   Morgan Del Gratta🇮🇹 · Federica Fabbri🇮🇹 · Michele Grossi🇨🇭 · Fabio Maltoni🇧🇪 · Davide Pagani🇮🇹 · Giovanni Pelliccioli🇮🇹 · Alessandro Vicini🇮🇹

   We investigate the origin of the unusually large electroweak (EW) radiative effects observed in the extraction of the spin-density matrix and related observables at colliders, focusing on leptonic Z-boson decays. We compute the Z-boson-decay spin-density matrix at next-to-leading order (NLO) and find that, while its analytic structure remains essentially unchanged with respect to leading order, the EW corrections induce a sizeable $-35\%$ shift in the spin-analysing-power parameter ${\eta }_{\ell }$. This effect alone accounts for the striking size of the corrections. For boosted Z bosons, we further show that the treatment of photon radiation in lepton-dressing algorithms significantly affects the extraction of spin-density-matrix coefficients at NLO and must be carefully controlled. To address these challenges, we propose a quantum tomography procedure that is applicable to any final state with one or more on-shell Z bosons that is robust under higher-order corrections. We illustrate its validity and limitations in $\text{pp}\to \text{ZZ}\to 4\ell$ and in heavy ($M_{\text{H}}>2M_{\text{Z}}$) Higgs-boson decay $\text{H}\to \text{ZZ}\to 4\ell$.

   hep-phhep-exJHEP(2026)·18 citations
2. 02*

   Collider probes of baryogenesis with maximal CP asymmetry

   Debasish Borah🇮🇳 · Kun Cheng🇺🇸 · Arnab Dasgupta🇺🇸 · Tao Han🇺🇸 · Keping Xie🇺🇸

   We propose a novel collider probe of baryogenesis at TeV scale by measuring decay asymmetries into particle and anti-particle final states. Motivated by the idea of Dirac leptogenesis, we consider an extension of the standard model with new colored and $SU(2{)}_L$ singlet particles in such a way that the out-of-equilibrium decay of heavy colored fermions creates equal and opposite CP asymmetries in two sectors, prevented from equilibrating with each other. While the TeV scale viability of this mechanism requires a resonantly enhanced CP asymmetry, the latter also plays a crucial role leading to observable decay asymmetries in colliders. In addition to discussing conventional signatures of such heavy colored particles, namely, mono-jet plus missing transverse energy, displaced vertex, colored track at hadron colliders, we also show the unique possibility of measuring decay asymmetries via forward-backward and charge asymmetries at future muon colliders. In addition to being a verifiable TeV-scale baryogenesis scenario, the model also predicts a singlet scalar dark matter candidate consistent with the required thermal dark matter properties near the Higgs resonance.

   hep-phastro-ph.COhep-exJHEP(2026)·0 citations
3. 03*

   Roles of $U(1)$ axial anomaly effects in cold and dense two-color QCD with $2+2$ flavors

   Manato Sakai🇯🇵 · Daiki Suenaga🇯🇵

   We explore phase structures and hadron mass spectra in cold and dense two-color QCD with $2+2$ flavors where the sign problem disappears. We particularly focus on $U(1)$ axial anomaly effects. We employ an $N_f=2+2$ linear sigma model based on the $SU(8)$ Pauli-Gürsey symmetry to describe negative-parity as well as positive-parity hadrons, for which low-energy excitations are appropriately described particularly in the baryon superfluid phase with light diquark condensates. As a result, the strange chiral condensate is found to be enhanced in the superfluid phase owing to the flavor-mixing structure of $U(1)$ axial anomaly effects. We also confirm this enhancement by means of the Nambu--Jona-Lasinio model. Besides, our present analysis predicts the existence of a novel superfluid phase where heavy diquarks condense in dense regime. The topological susceptibility with $2+2$ flavors from the viewpoints of the anomaly effects and chiral-symmetry restoration is investigated. Furthermore, we derive a complete inverse mass hierarchy for negative-parity diquarks with sufficient anomaly effects. Our findings are expected to provide future lattice simulations with useful information on flavor-symmetry violation from the $U(1)$ axial anomaly aspects in cold and dense two-color QCD medium.

   hep-phhep-latnucl-thPRD(2025)·2 citations
4. 04*

   Spectrum of Light Hexaquark States in Triquark-antitriquark Configuration

   Xuan-Heng Zhang🇨🇳 · Sheng-Qi Zhang🇨🇳 · Cong-Feng Qiao🇨🇳

   To understand the nature of $X(2075)$ and $X(2085)$ observed by the BESIII collaboration in the $p\bar{\Lambda }$ system, we systematically investigate the possibility that these states are compact hexaquark with triquark-antitriquark configurations for the first time. Within the framework of QCD sum rules, the mass spectrum and decay constants of such hexaquark states with quantum numbers $J^P=0^{-},0^{+},1^{-},1^{+}$ are studied. Consequently, six independent and nondegenerate hexaquark candidates are obtained, among which two $J^P=1^{-}$ states exhibit masses consistent with $X(2075)$, while the two $J^P=1^{+}$ states differ markedly from the mass of $X(2075)$ or $X(2085)$. The remaining two states with $J^P=0^{+}$ and $0^{-}$ may serve as predictions for potential compact hexaquark configurations. Furthermore, the possible decay modes of these hexaquark states are analyzed, which could be the experimental signatures for their identification.

   hep-phhep-exnucl-thPRD(2026)·7 citations
5. 05*

   Kinetic Freeze-Out Properties from Transverse Momentum Spectra of kaon, Pion, and (anti-)proton production in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV

   Ying Yuan🇨🇳

   In the framework of the multi-source thermal model employing the Tsallis distribution, the transverse momentum distributions of kaon, pion, and (anti -)proton production in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV with varying centrality are investigated. The transverse momentum spectra are appropriately characterized. The dependencies of parameters (average transverse momenta, effective temperature, and entropy index) on event centrality are determined. It is observed that the q parameters increase as the average number of particles participating in the collisions rises, which implies that the nuclear stopping degree elevates with the increase of collision centrality. The T value remains fundamentally consistent for the same particle under different collision parameters, suggesting that the kinetic freezing temperature of particle ejection in this collision system is independent of the collision parameters.

   hep-ph0 citations
6. 06*

   Baryons as linked vortices in QCD matter with isospin asymmetry

   Yu Hamada🇩🇪 · Muneto Nitta🇯🇵 · Zebin Qiu🇯🇵

   We investigate a baryonic structure in low-energy QCD via a model-independent way using the chiral perturbation theory at the leading order, in the presence of the baryon chemical potential ${\mu }_B$, the isospin chemical potential ${\mu }_I$, and the electromagnetic coupling. For such a scenario in the chiral limit, it has been known that the neutral pion winds like in the chiral soliton lattice, confined within an Abrikosov-Nielsen-Olesen (ANO) vortex of the charged pions. This structure undergoes a drastic transformation when the pion mass is introduced, i.e., both charged and neutral pions condense in the bulk, allowing two distinct types of vortices: the charged pions constitute a local ANO-like vortex, while the neutral pion configures a global vortex which is further attached to a domain wall also known as the chiral soliton. Remarkably, the ANO vortex forms a topological linking with the closed global vortex line, when ${\mu }_B$ exceeds its critical value as a function of ${\mu }_I$. The linking number has the physical meaning of the baryon number in view of the Wess-Zumino-Witten term. In this sense, the linked configuration realizes a stable Skyrmion-type solution, but innovatively without the Skyrme term. We therefore propose a novel phase of dense baryonic matter comprised of such vortices, which shall play a role in the low-energy QCD phase diagram.

   hep-phhep-thnucl-thJHEP(2026)·6 citations
7. 07*

   Muonium Spectroscopy as a Quantum Sensor for Ultralight Axion Dark Matter

   Feng Fang🇨🇳 · Kim Siang Khaw🇨🇳 · Ce Zhang🇬🇧 · Qiaoli Yang🇨🇳 · Liangwen Chen🇨🇳 · Jie Yang🇨🇳 · Lei Yang🇨🇳 · Zhiyu Sun🇨🇳

   High-intensity muon beams could enable a Muonium-based Axion Search through resonant quantum transitions between Hyperfine states (MASH). Combining theoretical calculations with simulation results, we demonstrate that such a muonium-based experimental approach could complement and tighten constraints on the axion-muon coupling beyond existing limits from the muon $g-2$ measurement, over the axion mass range of 18--130 $\mu$eV. These results establish a new spectroscopic channel in muonium that enables searches for axion and axion-like particle dark matter.

   hep-ph0 citations
8. 08*

   Thermal quarks and Polyakov loops in two-color dense QCD

   Yugo Kurebayashi🇯🇵 · Toru Kojo🇯🇵 · Daiki Suenaga🇯🇵

   We study confinement and deconfinement in dense two color QCD by analyzing the dynamics of thermal quarks and gluons. The Polyakov loop is used as a probe of the relevant thermal excitations, distinguishing quark and hadron dominated regimes in dense matter. To describe the Polyakov loop, we adopt both lattice informed phenomenological models and the massive Yang Mills framework. After calibrating these models at zero density, we investigate in medium modifications of the Polyakov loops and gluon propagators at finite temperature and density. Diquark gaps control the screening at zero temperature, whereas the screening due to thermal quarks is sensitive to the Polyakov loop. Inclusion of the Polyakov loop helps to reproduce lattice data at low temperature, suggesting that thermal excitations are predominantly hadronic rather than uncorrelated quarks.

   hep-phhep-latnucl-thUniverse(2025)·2 citations
9. 09*

   Scalaron dark matter dynamics: effects of Higgs non-minimal coupling to gravity

   Shibendu Gupta Choudhury🇮🇳 · Koushik Dutta🇮🇳 · Deep Ghosh🇮🇳

   One of the key features of the $R^2$-gravity is the embedding of a scalar field, scalaron, into the gravity sector. The scalaron interacts with the Standard Model (SM) matter fields through Planck-suppressed couplings. If the scalaron serves as a viable dark matter (DM) candidate, it can account for the lack of evidence of DM interactions beyond gravity in experimental and observational probes to date. The realization of the scalaron, as a cold DM candidate, depends on an induced trilinear interaction with the SM Higgs via its quartic self coupling. Here, we introduce a Higgs non-minimal coupling to gravity that additionally contributes to the induced trilinear interaction with its existing competing part, originated from the $R^2$-gravity. We study the interplay between these two contributions in the early universe, which determines both the initial conditions and evolution of the scalaron, leading to cold DM behavior at a later epoch. The trilinear interaction vanishes at the leading order for certain combinations of the Higgs non-minimal coupling ($\xi$) and the scalaron mass ($m$), thereby setting the scalaron density through misalignment mechanism, as in axions. In this case, the scalaron DM mass is obtained as, $2.7\mathrm{meV}\lesssim m\lesssim 0.7\mathrm{MeV}$. The lower limit on the mass is set by the fifth force constraints, whereas the upper bound arises from INTEGRAL/SPI limits on the excess gamma-ray flux due to scalaron decaying into two photons. On the other hand, when the trilinear interaction is non-zero and dominated by the Higgs quartic self coupling, the DM relic density is satisfied with $m\simeq 3.6$ meV. When the Higgs non-minimal coupling dominates, the mass lies within 10-770 meV. We also obtain, for the first time within the scalaron-Higgs mixed model, an upper bound on $|\xi m|$ of $1.5\times 10^{17}$ GeV, from Higgs mass measurement at the LHC.

   hep-phastro-ph.COgr-qcJCAP(2026)·1 citation
10. 10*

    ${\Lambda }_c(2910)$ and ${\Lambda }_c(2940)$ productions in $p\bar{p}$ annihilation

    Quan-Yun Guo🇨🇳 · Dian-Yong Chen🇨🇳

    In this work, we investigate the productions of ${\Lambda }_c(2910)$ and ${\Lambda }_c(2940)$ in the $p\bar{p}\to {\bar{\Lambda }}_c{D}^{0}p$ process by utilizing an effective Lagrangian approach, where both ${\Lambda }_c(2910)$ and ${\Lambda }_c(2940)$ are considered as $D^{\ast }N$ molecular states with $J^P=1/2^{-}$ and $3/2^{-}$, respectively. In addition to the $t$-channel $D$ and $D^{\ast }$ exchanges, the contribution from light-meson exchange is also considered. At $\sqrt{s}=10$ $\mathrm{GeV}$, our estimations indicate that the total cross sections for $p\bar{p}\to {\bar{\Lambda }}_c{D}^{0}p$ are $(130.7_{-103.9}^{+397.1})$ nb, where the central value is estimated with ${\Lambda }_r=1.1$ GeV, and the uncertainties are resulted from the variation of parameter ${\Lambda }_r$ from 1.0 GeV to 1.2 GeV. Our results indicate that the light meson exchange diagrams are very important, which provide a very large smooth background. Moreover, the estimations of the $D^{0}p$ invariant mass spectrum reveal that the peak structure between 2.9 and 3.0 GeV primarily originates from ${\Lambda }_c(2910)$, while the signal of ${\Lambda }_c(2940)$ is about one order smaller than that of ${\Lambda }_c(2910)$. Furthermore, the resulting Dalitz plot is estimated with $\sqrt{s}=8$ GeV. It is expected that our estimations in the present work can be tested by future experiments at $\bar{\mathrm{P}}\mathrm{ANDA}$.

    hep-phPRD(2026)·1 citation
11. 11*

    Impact of anisotropy on QCD phase structure and transport coefficients of quark matter

    Dhananjay Singh🇮🇳 · Arvind Kumar🇮🇳

    Employing the Polyakov chiral SU(3) mean field (PCQMF) model, we investigate how momentum-space anisotropy, characteristic of quark-gluon plasma (QGP) in ultrarelativistic heavy-ion collisions (uRHIC), impacts the thermodynamic behavior and transport coefficients of strongly interacting quark matter. The momentum anisotropy is introduced via a small deformation in the momentum distribution, quantified by a spheroidal parameter $\xi$, which deforms the distribution functions and captures anisotropic effects to linear order. The PCQMF model captures key non-perturbative aspects of QCD, like chiral symmetry breaking, deconfinement dynamics through Polyakov loop potential, and is extended here to accommodate momentum-space anisotropy. We compute the modifications induced by momentum-space anisotropy to key thermodynamic observables including pressure $p$, energy density $ϵ$, entropy density $s$, speed of sound squared $c_s^2$, and specific heat $c_v$, alongside key transport coefficients, such as shear viscosity $\eta$, bulk viscosity ${\zeta }_b$, and electrical conductivity ${\sigma }_{el}$. These coefficients are derived using the relativistic Boltzmann equation (RBE) under the relaxation time approximation (RTA). We find that even a weak anisotropy can lead to significant modifications in the thermodynamic response and transport behavior of quark matter. This underscores the importance of including momentum anisotropy for realistic modeling of the QCD medium across all energy regimes, from current studies at RHIC and LHC to future explorations of the high-density frontier at FAIR, NICA, and J-PARC.

    hep-phPRD(2026)·1 citation
12. 12*

    Probing Light Dark Matter with Cosmic Gravitational Focusing

    Shao-Feng Ge🇨🇳 · Liang Tan🇨🇳

    We investigate the possibility of using the cosmic gravitational focusing (CGF) to probe the minor light dark matter (DM) component whose mass is in the range of $(0.1\sim 100)$\,eV. Being a purely gravitational effect, the CGF offers a mode-independent probe that is complementary to the existing ways such as Lyman-$\alpha$ and $\Delta N_{\mathrm{eff}}$. Such effect finally leads to a dipole density distribution that would affect the galaxy formation and hence can be reconstructed with galaxy surveys such as DESI. Both the free-streaming and clustering limits have been studied with analytical formulas while the region in between is bridged with interpolation. We show the projected sensitivity at DESI with the typical phase space distribution of a freeze-in DM scenario as illustration.

    hep-phastro-ph.CO2 citations
13. 13*

    Coherently Enhanced Axion-Photon Conversion via Seeded Photons for Short-Pulse Axion Detection

    Xiangyan An🇨🇳 · Min Chen🇨🇳 · Jianglai Liu🇨🇳 · Yipeng Wu🇨🇳 · Peng Yuan🇺🇸 · Wenchao Yan🇨🇳 · Boyuan Li🇨🇳 · Feng Liu🇨🇳 · Zhengming Sheng🇨🇳 · Jie Zhang🇨🇳

    We propose a seeded axion-photon conversion scheme to enhance the sensitivity of light-shining-through-a-wall (LSW) experiments for axion detection, where the axions are generated from short pulse lasers and the usual resonant cavity is not applicable. By injecting a weak, coherent seed electromagnetic (EM) field into the axion-photon conversion region, the axion-induced EM field can constructively interfere with the seed field, amplifying the number of regenerated photons to a level exceeding that of the unseeded scenario. We evaluate the expected signal enhancement, statistical limits from Poisson counting with seed fluctuations and background, and the potential improvement in coupling sensitivity. Compared to a standard LSW setup, the seeded scheme can achieve orders-of-magnitude higher photon yield per axion, potentially surpassing resonance-enhanced experiments in certain parameter regimes. This approach presents a promising pathway to extend the reach of laboratory axion searches, particularly in scenarios where the resonant cavities are impractical.

    hep-phphysics.plasm-phPRD(2026)·2 citations
14. 14*

    Geometric Building Blocks of Effective Field Theory Amplitudes

    Timothy Cohen🇨🇭 · Xu-Xiang Li🇺🇸 · Zhengkang Zhang🇺🇸

    On-shell amplitudes are invariant under field redefinitions. Nonderivative field redefinitions have a natural interpretation as coordinate transformations on the target manifold. General field redefinitions, which may involve derivatives, can be viewed as coordinate transformations on the field configuration manifold. We present a unified perspective for the geometry of both the target manifold and the field configuration manifold for scalar effective field theories. In both cases, we identify vertices that can be used to build the tree-level amplitudes, with the property that they transform covariantly in the vacuum and on-shell limits. We identify a choice of metric on the field configuration manifold, for which amplitude expressions on the target manifold can be easily reproduced from their counterparts on the field configuration manifold. This clarifies the relation between the well-established framework of field space geometry and recent proposals for functional geometry.

    ↳ hep-thhep-phJHEP(2026)·6 citations
15. 15*

    Scalar Amplitudes from Fibre Bundle Geometry

    Mohammad Alminawi🇨🇭 · Ilaria Brivio🇨🇭 · Joe Davighi🇨🇭

    We compute tree-level $n$-point scattering amplitudes in scalar field theories in terms of geometric invariants on a fibre bundle. All 0- and 2-derivative interactions are incorporated into a metric on this bundle. The on-shell amplitudes can be efficiently pieced together from covariant Feynman rules, and we present a general closed formula for obtaining the $n$-point amplitude in this way. The covariant Feynman rules themselves can be derived using a generalization of the normal coordinate expansion of the fibre bundle metric. We demonstrate the efficiency of this approach by computing the covariant Feynman rules up to $n=10$ points, from which one can obtain the full amplitudes using our general formula. The formalism offers a prototype for obtaining geometric amplitudes in theories with higher-derivative interactions, by passing from the fibre bundle to its jet bundles.

    ↳ hep-thhep-phPRD(2026)·5 citations
16. 16*

    Probing the Parameter Space of Axion-Like Particles Using Simulation-Based Inference

    Pooja Bhattacharjee🇸🇮 · Christopher Eckner🇸🇮 · Gabrijela Zaharijas🇸🇮 · Gert Kluge🇳🇴 · Giacomo D'Amico🇪🇸

    Axion-like particles (ALPs), hypothetical pseudoscalar particles that couple to photons, are among the most actively investigated candidates for new physics beyond the Standard Model. Their interaction with gamma rays in the presence of astrophysical magnetic fields can leave characteristic, energy-dependent modulations in observed spectra. Capturing such subtle features requires precise statistical inference, but standard likelihood-based methods often fall short when faced with complex models, large number of nuisance parameters and limited analytical tractability. In this work, we investigate the application of simulation-based inference (SBI), specifically Truncated Marginal Neural Ratio Estimation (TMNRE), to constrain ALP parameters using simulated observations from the upcoming Cherenkov Telescope Array Observatory (CTAO). We model the gamma-ray emission from the active galactic nucleus NGC 1275, accounting for photon-ALP mixing, extragalactic background light (EBL) absorption, and the full CTAO instrument response. Leveraging the Swyft framework, we infer posteriors for the ALP mass and coupling strength and demonstrate its potential to extract meaningful constraints on ALPs from future real gamma-ray data with CTAO.

    ↳ astro-ph.HEhep-exhep-ph2 citations
17. 17*

    Nonlinear corrections to the nuclear heavy flavor structure functions

    F.Abdi🇮🇷 · B.Rezaei🇮🇷

    We study numerically the small-$x$ behaviour of the nuclear gluon distribution function $G^A(x,Q^2)$ at next-to-leading order (NLO) approximation of the Gribov-Levin-Ryskin-Mueller-Qiu, Zhu-Ruan-Shen (GLR-MQ-ZRS) nonlinear equation and quantify the impact of gluon recombination in the kinematic range of $x\le 10^{-2}$ and $Q^2\ge 5{\text{GeV}}^2$ respectively. The results are comparable to the Rausch-Guzey-Klasen (RGK) [J.Rausch, V.Guzey and M.Klasen, Phys. Rev. D 107, 054003 (2023)] nuclear gluon distributions and the nCTEQ15 parametrization at the corresponding $Q^2$ values. Using the solutions of $G^A(x,Q^2)$ in the framework of the nonlinear GLR-MQ-ZRS evolution equation, the linear and nonlinear behavior of the charm structure functions of nuclei per nucleon $F_2^{c\bar{c}-A}(x,Q^2)$ and $F_L^{c\bar{c}-A}(x,Q^2)$ are considered. The results reveal that nonlinear corrections play an important role in charm nuclear reduced cross sections at small-$x$ and low $Q^2$ values. The computed results are compared with experimental data from the H1 and ZEUS Collaborations.

    ↳ nucl-thhep-phPRC(2025)·0 citations
18. 18*

    Probing Initial State Clustering through Photon Anisotropic Flow in 7A TeV ${}^{16}$O+${}^{16}$O Collisions at the LHC

    Sanchari Thakur🇮🇳 · Pingal Dasgupta🇭🇺 · Rupa Chatterjee🇮🇳 · Sinjini Chandra🇮🇳 · Sidharth K. Prasad🇮🇳

    The presence of $\alpha$ clustered structures in light nuclei can enhance the initial spatial anisotropies in relativistic nuclear collisions relative to those arising from nuclei with uniform density distributions. Thus, observables that are strongly sensitive to the initial geometry can be a more efficient probe of the clustered structures than observables dominated by final state dynamics. We investigate the collisions of $\alpha$ clustered oxygen nuclei at $\sqrt{s_{NN}}=7$A TeV at the LHC using the GLISSANDO initial state model along with the MUSIC event-by-event hydrodynamical framework. The tetrahedral $\alpha$ clustered structure of ${}^{16}$O leads to significantly larger initial triangular eccentricity ${ϵ}_3$ than collisions with uniform density distributions especially in the most central events. The spatial eccentricity ${ϵ}_2$ is found to be relatively less sensitive to the initial state clustered structure. The production of thermal photons is estimated to be only marginally influenced by clustering for both central as well as peripheral collisions. In contrast, the photon triangular flow coefficient $v_3(p_T)$ is strongly affected by initial state clustering resulting in substantially larger values in both central and peripheral collisions. An experimental determination of photon anisotropic flow together with the ratios of flow coefficients in ${}^{16}$O+${}^{16}$O collisions therefore expected to provide valuable insight into the possible clustered structure in light nuclei and also to constrain parameters in theoretical modeling.

    ↳ nucl-thhep-phEPJC(2026)·0 citations
19. 19*

    High energy gamma rays and neutrinos from the Sun, Jupiter and Earth

    Pablo de la Torre🇪🇸 · Miguel Gutiérrez🇪🇸 · Manuel Masip🇪🇸 · Alejandro Oliver🇪🇸

    Cosmic rays reaching the atmosphere of an astrophysical object produce showers of secondary particles that may then escape into space. Here we obtain the flux of gamma rays and neutrinos of energy $E>10$ GeV emitted by the Sun, Jupiter and Earth. We show that, while the solar magnetic field induces a flux of gamma rays from all the points on the Sun's surface, the dipolar magnetic field in the planets implies high energy photons only from the very peripheral region. Neutrinos, in contrast, can cross these objects and emerge from any point on their surface. The emission from these astrophysical objects exceeds the diffuse flux from cosmic ray interactions with the interstellar medium and has a distinct spectrum and gamma ray to neutrino ratio.

    ↳ astro-ph.HEhep-phApJ(2025)·2 citations
20. 20*

    Effects of mean-field momentum dependence on pion production in intermediate-energy heavy-ion collisions

    Xin Li🇨🇳 · Si-Pei Wang🇨🇳 · Zhen Zhang🇨🇳 · Rui Wang🇨🇳 · Jie Pu🇨🇳 · Chun-Wang Ma🇨🇳 · Lie-Wen Chen🇨🇳

    Pion production in heavy-ion collisions at intermediate energies provides an important probe of the collision dynamics and nuclear matter equation of state, especially the high-density behavior of the symmetry energy. Using the lattice Boltzmann-Uehling-Uhlenbeck transport model with a recently developed nuclear effective interaction based on the so-called N$5$LO Skyrme pseudopotential, we investigate the effects of the momentum dependence of nucleon mean-field potentials on the pion production in Au+Au collisions at a beam energy of $1.23$~GeV/nucleon. We find that a stronger momentum dependence, for which the nucleon mean-field potentials increase faster with momentum, generally suppresses pion production. This feature can be understood in terms of the mean-field-induced modification of nucleon high-momentum phase space during the compression stage: a stronger momentum dependence can reduce the relative fraction of high-momentum nucleons in heavy-ion collisions, thereby suppressing the production of $\Delta$ resonances and pions.

    ↳ nucl-thhep-phnucl-exPLB(2026)·6 citations
21. 21*

    Radiation of breathing vortex electron packets in magnetic field

    G. V. Zmaga · G. K. Sizykh🇷🇺 · D. V. Grosman🇷🇺 · Qi Meng · Liping Zou🇨🇳 · Pengming Zhang🇨🇳 · D. V. Karlovets🇷🇺

    When a vortex electron with an orbital angular momentum (OAM) enters a magnetic field, its quantum state is described with a nonstationary Laguerre-Gaussian (NSLG) state rather than with a stationary Landau state. A key feature of these NSLG states is oscillations of the electron wave packet's root-mean-square (r.m.s.) radius, similar to betatron oscillations. Classically, such an oscillating charge distribution is expected to emit photons. This raises a critical question: does this radiation carry away OAM, leading to a loss of the electron's vorticity? To investigate this, we solve Maxwell's equations using the charge and current densities derived from an electron in the NSLG state. We calculate the total radiated power and the angular momentum of the emitted field, quantifying the rate at which a vortex electron loses its energy and OAM while propagating in a longitudinal magnetic field. We find both the radiated power and the angular momentum losses to be negligible indicating that linear accelerators (linacs) appear to be a prominent tool for maintaining vorticity of relativistic vortex electrons and other charged particles, at least in the quasi-classical approximation.

    ↳ quant-phhep-phPRA(2026)·4 citations
22. 22*

    Decaying superfluid turbulence near an anomalous non-thermal fixed point

    Niklas Rasch · Thomas Gasenzer🇩🇪

    We investigate anomalously slow coarsening in a dilute two-dimensional (2d) superfluid closed with respect to particle and energy exchange with the environment. The dynamics is demonstrated to be closely connected to both, a non-thermal fixed point (NTFP) in a far-from-equilibrium quantum system, and to Kraichnan-Kolmogorov turbulence. During a universal dynamical regime associated with an anomalous NTFP, vortex dynamics are understood to be governed by three-vortex collisions that trigger vortex-antivortex annihilation events, leading to a subdiffusive decay of the vortex density and thus growth of the characteristic inter-defect length scale, ${\ell }_{\text{v}}\sim t^{\beta }$ with $\beta \approx 1/5$. It is found that, during the same time when this power law in time is seen, the moments of the superfluid velocity circulation $\Gamma$ around an area of spatial extent $r$ exhibit power-law scaling ${\Gamma }^2(r)\sim r^{8/3}$, in agreement with Kraichnan-Kolmogorov predictions for an inverse energy cascade in the inertial range, in a driven-open setting. Moreover, in high-order moments, intermittent deviations from linear scaling ${\Gamma }^{2p}(r)\sim [{\Gamma }^2(r){]}^p$ are observed that are consistent with bifractal intermittency corrections previously measured in fully developed classical turbulence. These results establish a quantitative link between decaying quantum turbulence in a closed superfluid and universal dynamics near a non-thermal fixed point. Notably, the subdiffusive decay exponent $\beta \approx 1/5$ deviates significantly from values reported for classical systems.

    ↳ cond-mat.quant-gashep-phPRA(2026)·1 citation
23. 23*

    Towards the Giant Radio Array for Neutrino Detection (GRAND): the GRANDProto300 and GRAND@Auger prototypes

    GRAND Collaboration: Jaime Álvarez-Muniz🇪🇸 · Rafael Alves Batista🇫🇷 · Aurélien Benoit-Lévy🇫🇷 · Teresa Bister🇳🇱 · Martina Bohacova🇨🇿 · Mauricio Bustamante🇩🇰 · Washington Carvalho🇵🇱 · Yiren Chen🇨🇳 · LingMei Cheng🇨🇳 · Simon Chiche🇧🇪 · Jean-Marc Colley🇫🇷 · Pablo Correa🇫🇷 and 108 other authors

    The Giant Radio Array for Neutrino Detection (GRAND) is a proposed multi-messenger observatory of Ultra-High-Energy (UHE) particles of cosmic origin. Its main goal is to find the long-sought origin of UHE cosmic rays by detecting large numbers of them and the secondary particles created by their interactions like gamma rays and neutrinos. The GRAND Collaboration plans to achieve this using large arrays of radio antennas that look for the radio signals emitted by the air showers initiated by the interactions of the UHE particles in the atmosphere. Since 2023, three small-scale prototype GRAND arrays have been in operation: GRAND@Nançay in France, GRAND@Auger in Argentina, and GRANDProto300 in China. Together, their goal is to validate the detection principle of GRAND under prolonged field conditions, achieving efficient, autonomous radio-detection of air showers. We describe the hardware, software, layout, and operation of the GRAND prototypes. Using their data, we show a first characterization of the local electromagnetic environment of each site and a measurement of the Galactic synchrotron emission. Despite challenges, the successful operation of the prototypes confirms that the GRAND instrumentation is apt to address the goals of the experiment and lays the groundwork for its ensuing stages.

    ↳ astro-ph.IMhep-exhep-phJINST(2026)·4 citations
24. 24*

    Buchdahl limit of compact stars in presence of Weyl anomaly

    Waleed El Hanafy🇪🇬 · G.G.L. Nashed🇪🇬

    We setup an anisotropic compact star model in presence of Weyl ``trace" anomaly. We derive an exact interior solution which determines the contribution of the vacuum trace anomaly. We introduce a dimentionless parameter, $\beta$, to characterize this contribution. Applying appropriate matching conditions with the exterior solution, we determine the model parameters in terms of the Weyl anomaly parameter $\beta$ and the compactness parameter, $C=\frac{2GM}{c^2\mathcal{R}}$ where $M$ and $\mathcal{R}$ are the mass and the radius of the star. We investigate the parameter space $\{\beta ,C\}$ and the corresponding modifications of Buchdahl limit on the maximum compactness. We use astrophysical observations of mass and radius of the pulsar PSR J0740+6620 to constrain the Weyl anomaly parameter $\beta$. Also, we investigate the Mass-Radius diagram with other observational constraints from NICER and LIGO/Virgo collaboration.

    ↳ gr-qchep-phhep-thPLB(2025)·2 citations

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