Tue·Oct 21, 2025Tuesday·October 21, 2025

1. 01*

   A new determination of higher-order QCD corrections to hadronic $\tau$ decays

   Gauhar Abbas🇮🇳 · Vartika Singh🇮🇳

   We employ \textit{Levin-type sequence transformations} to accelerate the convergence of the perturbative fixed-order expansion of the QCD correction ${\delta }^{(0)}$ in terms of the strong coupling ${\alpha }_s$. The method efficiently resums the series, yielding a stable and self-consistent determination of higher-order QCD corrections to hadronic $\tau$ decays, consistent with existing results. We find ${\delta }_{\text{Levin-FOPT}}^{(0)}=0.2089\pm 0.0040\pm 0.0060_{{\alpha }_s}$, and predict $c_{5,1}=278_{-19}^{+27},c_{6,1}=3375_{-209}^{+489},c_{7,1}=(2.03_{-0.25}^{+0.41})\times 10^4.$ Our results demonstrate that Levin-type transformations provide an efficient framework for analyzing asymptotic perturbative series, and studying the higher order perturbative behaviour of the hadronic $\tau$ decays.

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

   Determination of proton PDF uncertainties with Markov chain Monte Carlo

   Peter Risse🇩🇪 · Nasim Derakhshanian🇵🇱 · Tomas Jezo🇩🇪 · Karol Kovarik🇩🇪 · Aleksander Kusina🇵🇱

   We present an analysis of parton distribution functions (PDFs) of the proton using Markov Chain Monte Carlo (MCMC) methods. The MCMC approach naturally implements Bayes' theorem and thus provides a means to directly sample the underlying probability distribution - in this case the probability distribution of the PDF parameters. This allows for a straightforward propagation of the resulting uncertainties into any PDF-dependent observable, preserving their simple probabilistic interpretation. In our analysis we include a broad set of deep inelastic scattering data from HERA, BCDMS and NMC experiments along with the Drell-Yan, $W$ and $Z$ boson data from LHC and Tevatron experiments, which combined with theoretical calculations at next-to-next-to-leading order in QCD allow for realistic determination of PDFs. The main focus of this analysis is to explore alternative methods for PDF uncertainty estimation that are more firmly grounded in statistical principles. We show that the flexibility of the Bayes framework, allowing e.g. to account for non-Gaussianity or inconsistencies of data sets, is crucial to extract realistic uncertainties when such assumptions are not fulfilled. We also demonstrate that MCMC allows one to determine the $\Delta {\chi }^2$ value corresponding to a given confidence level in the sample, which can in turn be used as a statistically well-founded tolerance criterion used in the Hessian method, thus addressing one of its main long-standing drawbacks.

   hep-phPRD(2026)·3 citations
3. 03*

   Axion condensates in neutron stars and radial oscillation modes

   Antonio Gómez-Bañón🇪🇸 · Pantelis Pnigouras🇪🇸 · José A. Pons🇪🇸

   Light QCD axions, introduced to solve the strong CP problem, may form condensates inside neutron stars, giving rise to a novel ground state of dense matter. We investigate how such axion condensates modify the equilibrium structure and radial oscillation spectrum of neutron stars. Using a realistic neutron star model with the BSk26 equation of state, and solving the coupled Tolman-Oppenheimer-Volkoff and Klein-Gordon equations together with a linear perturbation analysis, we find two distinct families of quasinormal modes: weakly damped fluid-dominated oscillations and highly damped axion modes. The coupling between the fluid and the axion field introduces axion-induced damping of radial oscillations, with decay timescales of order seconds for kHz axion masses. Modes with frequencies above the axion mass are strongly damped, while those below remain unaffected. Although neutron star radial oscillations are difficult to observe, our results suggest that extensions of this work can turn neutron star seismology into a novel probe of the axion properties.

   hep-phastro-ph.HEPRD(2026)·1 citation
4. 04*

   Nucleon axial form factors in generalized nonlocal chiral effective theory

   Y. Salamu🇨🇳 · Haximjan Abdusattar🇨🇳

   In this work, we first investigate the chiral transformation properties of the nonlocal pion field operator and construct a generalized nonlocal chiral Lagrangian that is invariant under $\mathrm{SU}(2)$ chiral symmetry transformations. As a simple application, we then calculate the leading and next-leading order pion one loop corrections to the nucleon axial form factors within nonlocal chiral perturbation theory. Then, we fit the next leading order and next-next leading order low energy coupling constants (LECs) to lattice QCD data. The fitted results show that the nonlocal LECs are comparatively smaller than their local counterparts. Finally, using these LECs, we compute the $Q^2$ dependence of the nucleon axial form factors. The numerical results indicate that the nonlocal nucleon axial form factors are consistent with lattice QCD data in a wide ${\mathrm{Q}}^2$ range, up to ${\mathrm{Q}}^2=1{\mathrm{GeV}}^2$

   hep-phPRD(2026)·1 citation
5. 05*

   Semileptonic decay and form factors of ${\Omega }_b^{-}\to {\Omega }_c^{0}e\overline{{\nu }_e}$

   Kinjal Patel🇮🇳 · Kaushal Thakkar🇮🇳

   We investigated the heavy-to-heavy semileptonic decay ${\Omega }_b^{-}\to {\Omega }_c^{0}e\overline{{\nu }_e}$ within the framework of the Hypercentral Constituent Quark Model (HCQM). The ground-state masses of the involved baryons were evaluated by numerically solving the six-dimensional hyperradial Schrödinger equation, incorporating both hyper-Coulomb and linear confinement potentials along with spin-dependent interactions. The Heavy Quark Effective Field Theory (HQET) form factors are computed up to the subleading order, incorporating $1/m_Q$ corrections that account for finite mass effects beyond the heavy-quark symmetry limit. These form factors were then employed to analyse the heavy-to-heavy semileptonic decay rate via helicity formalism. The decay width and branching ratio results were compared to those obtained using various theoretical approaches.

   hep-phEPJA(2026)·3 citations
6. 06*

   Heavy flavor transport in the QGP medium

   Bruno Scheihing-Hitschfeld🇺🇸

   I review recent developments on heavy flavor transport in the QGP medium, along two directions. The first is the transport of individual open heavy quarks. Leveraging the tools of heavy quark effective theory, recent work revealed a novel connection between the evolution equation of the heavy quark phase space distribution, the conditions for kinetic equilibration to take place, and a non-perturbatively defined expectation value of a Wilson loop characterized by the heavy quark velocity. Using these developments, I discuss results from a first exploration of the ensuing stopping and equilibration dynamics of heavy quarks in a strongly coupled environment. The second direction is the transport of quarkonia, bound states of heavy quarks, where novel Generalized Gluon Distributions have been recently defined and calculated in the framework of potential non-relativistic QCD. I discuss their application to the dynamics of quarkonium in heavy-ion collisions, highlighting the need to account for non-Markovian effects in the interactions between the heavy quark pair and quark-gluon plasma -- which have thus far resisted a systematic characterization.

   hep-phnucl-thPoS(2026)·0 citations
7. 07*

   Neutrino Oscillation Prospects with a Dual-Baseline Beam from BNL to SNOLAB and SURF

   Nishat Fiza🇵🇪 · Mehedi Masud🇰🇷 · Kim Siyeon🇰🇷 · Guang Yang🇺🇸

   The Electron-Ion Collider (EIC) is a next-generation accelerator primarily designed to study the internal structure of nucleons through high-precision electron-hadron collisions. In this work, we explore the feasibility of employing a 1 MW fraction of the EIC proton beam to generate a high-intensity GeV-scale neutrino beam for long-baseline oscillation studies. We have simulated proton-target interactions and optimize the resulting neutrino fluxes for water-based liquid scintillator (WbLS) detectors located at distinct baselines of 900 km and 2900 km. Oscillation analyses performed with GLoBES show that extended baselines allow access to multiple oscillation maxima, significantly enhancing sensitivity to leptonic CP violation. The study also examines the interplay between matter effects and the intrinsic CP violating phase in shaping observable asymmetries. We note that simplified systematics and no backgrounds are used in this analysis to establish the baseline physics potential. These results suggest that the EIC proton beam could provide a novel and complementary source for precision neutrino physics, extending the scientific reach of the EIC program.

   hep-phJHEP(2026)·0 citations
8. 08*

   A Way of Axion Detection with Mass $10^{-4}\text{-}10^{-3}$eV Using Cylindrical Sample with Low Electric Conductivity

   Aiichi Iwazaki🇯🇵

   A dark matter axion with mass $m_a$ induces an oscillating electric field in a cylindrical sample placed under a magnetic field $B_0$ parallel to the cylinder axis. When the cylinder is made of a highly electrically conductive material, the induced oscillating current flows only at the surface. In contrast, if the cylinder is composed of a material with small conductivity, e.g. $\sigma =10^{-3}\text{eV}$, the electric current flows inside the bulk of the cylinder. Within the QCD axion model, the current $I$ is estimated as $I(\sigma =10^{-3}\text{eV})\simeq 2.8\times 10^{-14}\text{A}{g}_{\gamma }(R/6\text{cm}{)}^2(\sigma /10^{-3}\text{eV}\left)\right(B_0/15\text{T}\left)\right(10/ϵ\left)\right({\rho }_a/0.3\mathrm{GeVc}{\mathrm{m}}^{-3}{)}^{1/2}$ for $m_a=10^{-4}$eV, with radius $R$, permittivity $ϵ=10$ of the cylinder and axion energy density ${\rho }_a$, where $g_{\gamma }$ is model dependent parameter; $g_{\gamma }(\text{KSVZ})=-0.96$ and $g_{\gamma }(\text{DFSZ})=0.37$. Because the current is proportional to $R^2$, using large sample with $R=80$cm, we have large signal-noise ratio ( $>1$ ) even in temperature $T=4$K, $I(\sigma =10^{-3}\text{eV})/I_n(\sigma =10^{-3}\text{eV})\times \sqrt{\delta \omega \delta t_{ob}/2\pi }\simeq 1.1g_{\gamma }(4\text{K}/T{)}^{1/2}(L/100\text{cm}{)}^{1/2}(R/80\text{cm})(B_0/7\text{mbox}T)({\rho }_a/0.3\mathrm{GeVc}{\mathrm{m}}^{-3}{)}^{1/2}(\delta {\mathrm{t}}_{\mathrm{ob}}/10^3\text{s}{)}^{1/2}$ for $m_a=10^{-4}\text{eV}$ with $ϵ=10$ and $\sigma =ϵm_a$, where thermal noise is $I_n=\sqrt{2T\delta \omega /\pi R_c}$ with $\delta \omega =10^{-6}{m}_a$ and resistance $R_c=L/(\sigma \pi R^2)$ of the cylinder with length $L$. Although a superconducting solenoid sufficiently large to accommodate such a sample is required, the detection of dark matter axions in our proposal may be feasible in the mass range $m_a=10^{-4}\text{-}10^{-3}\text{eV}$.

   hep-phhep-exPTEP(2026)·2 citations
9. 09*

   Possible mixing between elementary and bound state fields in the $t\bar{t}$ production excess at the LHC

   Yoshiki Matsuoka🇯🇵

   Recent report by CMS Collaboration on the excess of top and anti-top pair production is studied, under the hypothesis of the coexistence of a toponium $({\eta }_t)$ and an additional elementary field $(\Psi )$. We examine the scenario where toponium and an additional field are mixed, and consider the plausible scenarios in that case. Two scenarios are examined: one is the minimal model with $\Psi$ close to the inert Higgs doublet, and the other is embedded into the two Higgs doublet models (2HDM), where $\Psi$ is one of the two Higgs scalars after transforming the basis. The value of the each coupling constant is restricted by the Multicritical Point Principle (MPP). Consistency with the data gives constraints on a mixing angle $\theta (-45^{\circ }\le \theta \le 45^{\circ })$, with which the mass eigenstate ${\Psi }^{\prime }$ contributing to the excess is defined by ${\Psi }^{\prime }=\Psi \cos \theta +{\eta }_t\sin \theta$. The obtained results are $|\theta |\le 13^{\circ }$ for the minimum scenario, and $|\theta |\le 1^{\circ }$ for the second scenario of 2HDM(Type II and Y). We also briefly discuss the comparison with Type I and X.

   hep-phhep-exEPJC(2026)·5 citations
10. 10*

    Bayesian inference of the magnetic component of quark-gluon plasma

    Yu Guo🇨🇳 · Jinfeng Liao🇺🇸 · Shuzhe Shi🇨🇳

    The chromo-magnetic monopoles (CMM), emergent topological excitations of non-Abelian gauge fields carrying chromo-magnetic charge, have long been postulated to play an important role in the vacuum confinement of quantum chromodynamics (QCD), the deconfinement transition at temperature $T_c\approx 160\mathrm{MeV}$, as well as the strongly coupled nature of quark-gluon plasma (QGP). While such CMMs have been found to provide solutions for challenging puzzles from heavy-ion collision measurements, they were typically introduced as model assumptions in the past. Here we show how their very existence can be determined and their abundance extracted in a data-driven way for the first time. Using the \textsc{cujet3} framework for calculations of jet energy loss and analyzing a comprehensive experimental data set for nuclear modification factor ($R_{\mathrm{AA}}$) and elliptic flow ($v_2$) of high-transverse-momentum hadrons, the fraction of CMMs in the QGP is obtained by Bayesian inference and is found to be substantial in the $1\sim 2T_c$ region. The posterior CMM fraction is further validated by excellent agreement with additional data and is also shown to predict QGP transport properties quantitatively consistent with the state-of-the-art knowledge.

    hep-ph2 citations
11. 11*

    Dynamic Lasing of Axion Clusters

    Liang Chen🇨🇳 · Thomas W. Kephart🇺🇸

    We examine high-density axion clusters under gravitational compression. These are transient events in which the majority of axions are rapidly converted into photons, with some configurations producing photon signals with distinctive and characteristic patterns. We estimated the mass of the remnant objects and note that some could be black holes while in some cases it may be possible to identify the emitted photons with a robust class of fast radio bursts.

    hep-ph0 citations
12. 12*

    Imprints of a Second Order Electroweak Phase Transition on the Stochastic Gravitational Wave Background

    V.K. Oikonomou🇬🇷

    In this work we shall study the impact of a second order electroweak phase transition occurring at $\sim 150$GeV on the energy spectrum of the stochastic gravitational background. Specifically, we assume that the non-minimally coupled Higgs field controls the inflationary era, we find the reheating temperature for the Higgs inflationary model and we demonstrate that the Higgs effective potential exhibits a very weak first order phase transition. This weak first order phase transition is an indication that the electroweak phase transition may not actually proceed as a first order phase transition, but it will proceed as a crossover or second order phase transition. This second order phase transition proceeds with the Higgs field slow-rolling its potential toward to its new minimum. This slow-rolling may deform the radiation domination total equation of state, and the aim of this work is to pinpoint the observational imprints of this total equation of state deformation on the energy spectrum of the primordial gravitational waves, that affects modes that enter the horizon at temperatures $T\sim 150$GeV or lower.

    hep-phastro-ph.COgr-qchep-thEPJC(2025)·3 citations
13. 13*

    $3^{++}$ light meson family

    Hao Chen🇨🇳 · Yan-Yue Fan🇨🇳 · Yun-Hai Zhang🇨🇳 · Cheng-Qun Pang🇨🇳

    As members of the $J^{PC}=3^{++}$ light meson family, the assignments of the $a_3(1875)$, $a_3(2030)$, $a_3(2275)$, $f_3(2050)$, and $f_3(2300)$ states remain unclear. In this work, we investigate the mass spectra and the Okubo-Zweig-Iizuka-allowed two-body strong decays of the $3^{++}$ light meson family using the modified Godfrey-Isgur quark model and the quark-pair creation model. We explore the identification of the $a_3(1875)$, $a_3(2030)$, $a_3(2275)$, $f_3(2050)$, and $f_3(2300)$ states. Additionally, we predict the masses and widths of the higher excitations in the $3^{++}$ light meson family.

    hep-ph0 citations
14. 14*

    Possibility To Study Photon Scattering By Proton In The Reaction e+p -> e+p+gamma

    A.I. Lvov🇷🇺 · V.A. Petrunkin🇷🇺 · S.G. Popov🇷🇺 · B.B. Wojtsekhowski🇺🇸

    A theoretical possibility to determine the proton Compton scattering cross section from the reaction $ep\to ep\gamma$ is studied in the kinematics with a small transversal momentum transfer in the electron leg. With the exception of the region of forward photon directions and extreme photon energies close to the maximum ones or zero, registration of the particles $\gamma$ and $p$ in the final state can enable one to distinguish the sub-process of the Compton scattering from the electron bremsstrahlung background and, owing to complete kinematical reconstruction of each individual event, measure in detail energy and angular dependence of the $\gamma p$-scattering cross section. The count rate expected with a storage ring like NEP having luminosity $L\approx 2\cdot 10^{35}$ cm${}^{-2}\cdot$ sec${}^{-1}$ as projected is $\approx 10^3$ events/hour. Such measurements might help to determine proton polarizabilities with high statistical accuracy.

    hep-phnucl-ex0 citations
15. 15*

    The window on heavy charged dark matter was never open

    Daniele Perri🇵🇱 · Glennys Farrar🇺🇸

    There is a claim in the literature that charged dark matter particles in the mass range $100(q_{\mathrm{X}}/e{)}^2\mathrm{TeV}\le m_{\mathrm{X}}\le 10^8(q_{\mathrm{X}}/e)\mathrm{TeV}$ are allowed, based on arguing that heavy charged particles cannot reach the Earth from outside the magnetized region of the Milky Way (Chuzhoy-Kolb, 2009). We point out that this claim fails for physical models for the Galactic magnetic field. We explicitly confirm our argument by simulating with the software CRPropa the trajectories of heavy charged dark matter in models of the Galactic magnetic field.

    hep-phastro-ph.HE3 citations
16. 16*

    Searching for generalized neutrino interactions in direct detection experiments with E{\nu}ES

    Jesús Miguel Celestino-Ramírez🇲🇽 · F. J. Escrihuela🇪🇸 · L. J. Flores🇲🇽 · O. G. Miranda🇲🇽 · R. Sánchez-Vélez🇲🇽

    We investigate the sensitivity of present and future direct detection experiments to generalized neutrino interactions (GNI) through elastic neutrino electron scattering. Using data from LUX-ZEPLIN, PandaX-4T, and XENONnT, we derive constraints on vector, axial-vector, scalar, and tensor effective couplings, and compare them with existing limits. Our results show that current xenon-based detectors already provide competitive bounds, with XENONnT offering the most stringent constraints due to its larger exposure and reduced backgrounds. Among the GNI couplings, the scalar contributions remain more weakly constrained, while tensor interactions yield the strongest limits. We also present projected sensitivities for the DARWIN experiment, showing potential improvements. These results demonstrate the capability of direct detection experiments, originally designed for dark matter searches, to provide complementary and competitive constraints on generalized neutrino interactions.

    hep-phJHEP(2026)·4 citations
17. 17*

    The Lorentz-Violating effects in charged particle systems

    E.Maciel🇧🇷 · M. A. Anacleto🇧🇷 · K.E.L. Farias🇧🇷 · E. Passos🇧🇷

    We investigate the relativistic dynamics of a spin half particle in the presence of a Lorentz-violating background within the framework of effective field theory. A modified Dirac Hamiltonian is considered, arising from a CPT odd coupling involving the Lorentz violating gauge tensor of the Standard Model Extension (SME). The velocity and effective force operators are derived from the Heisenberg equations of motion. Using Ehrenfest s theorem and the correspondence principle, we obtain the classical limit of the dynamics and identify an effective force exhibiting a generalized Lorentz force structure. This formalism is applied to a Penning trap system, known for its high precision measurements of charged particle properties. Our analysis shows that the effective cyclotron frequency acquires a correction due to the Lorentz violating term, leading to deviations in the particle trajectory and offering a potentially observable signature of Lorentz violation in precision experiments. By comparing our results with current bounds from high precision Penning traps, we establish an upper limit on the Lorentz violating coupling, $\bar{g}{k}_{AF}\lesssim 2.32\times 10^4{\mathrm{eV}}^{-1}$ corresponds to LIV effects. This bound is compatible with the interpretation of an effective Lorentz violation, consistent with current observational constraints, and it reinforces the phenomenological nature of the term under consideration, in agreement with previous analyses based on cosmological birefringence and photon propagation in a Lorentz violating background.

    hep-ph0 citations
18. 18*

    Radiative lepton model in a non-invertible fusion rule

    Takaaki Nomura🇨🇳 · Hiroshi Okada🇨🇳 · Yoshihiro Shigekami🇨🇳

    We propose a radiatively induced lepton mass model introducing a $Z_2$ gauging $Z_5$ fusion rule. In our framework, the charged-lepton mass matrix is generated at one-loop level via dynamical breaking of the fusion rule. On the other hand, the neutrino mass matrix is induced at the one-loop level without breaking the fusion rule. As a direct consequence of the loop induced charged lepton masses, we can also consider lepton flavor violations, electron and muon $g-2$, and charged-lepton electric dipole moments that come into our valid phenomenological discussion. Then, we perform numerical analysis and show some interesting tendency on the Dirac $CP$ phase, two Majorana phases, charged-lepton electric dipole moments and the neutrinoless double beta decay, all of which depends on their arguments where we fix the absolute values of our free parameters in order to satisfy experimental data of the lepton masses and mixing angles.

    hep-phPRD(2026)·12 citations
19. 19*

    Deep Neural Network extraction of Unpolarized Transverse Momentum Distributions

    I. P. Fernando🇺🇸 · D. Keller🇺🇸

    Building on the first-ever application of neural networks in TMD phenomenology: "Extraction of the Sivers function with deep neural networks", we now present a momentum space, physics-informed deep learning framework for the direct extraction of unpolarized transverse momentum dependent parton distributions (TMDs) from fixed target Drell-Yan data (E288, E605). Rather than transforming to impact-parameter space, we remain in k and embed a normalized integrand s(x, k; Q) whose auto-convolution produces the observed qT spectra. The extraction proceeds in two steps. Stage I learns the structure kernel S(qT , x1, x2; QM ) by regressing the cross-section with known kinematic prefactors and charge-weighted PDF combinations factored out; experimental and PDF uncertainties are propagated with Monte Carlo replicas. Stage II reconstructs s(x, k; Q) with an end-to-end differentiable k quadrature layer. Applied to Fermilab cross-section data from experiments E288 and E605, the method reproduces the measured qT spectra across Q and yields x and Q dependent TMDs that broaden with Q, with uncertainty bands that consistently propagate experimental, PDF, algorithmic and methodological components. The approach is minimally biased (no factorized Ansatze and no bT transform) and provides a transferable template for polarized TMDs and related QCD inverse problems.

    hep-phPRD(2026)·11 citations
20. 20*

    Predicting charmed-strange molecular tetraquarks with $K^{(\ast )}$ and $T$-doublet charmed or anticharmed meson

    Fu-Lai Wang🇨🇳 · Si-Qiang Luo🇨🇳 · Xiang Liu🇨🇳

    In this work, we first present a systematic investigation of the $T_{\bar{c}\bar{s}}$-type charmed-strange molecular tetraquark candidates composed of a $K^{(\ast )}$ meson and a $T$-doublet anticharmed meson using the one-boson-exchange model, which exhibit exotic flavor content $\bar{c}\bar{s}qq$. Our results suggest that the $K^{\ast }{\bar{D}}_1$ states with $I(J^P)=0(0^{-},1^{-})$ and the $K^{\ast }{\bar{D}}_2^{\ast }$ states with $I(J^P)=0(1^{-},2^{-})$ represent the most promising candidates of the $T_{\bar{c}\bar{s}}$-type charmed-strange molecular tetraquarks, while the coupled $K{\bar{D}}_1/K^{\ast }{\bar{D}}_1/K^{\ast }{\bar{D}}_2^{\ast }$ system with $I(J^P)=0(1^{-})$ and the coupled $K{\bar{D}}_2^{\ast }/K^{\ast }{\bar{D}}_1/K^{\ast }{\bar{D}}_2^{\ast }$ system with $I(J^P)=0(2^{-})$ can only be regarded as the possible candidates of the $T_{\bar{c}\bar{s}}$-type charmed-strange molecular tetraquarks. We further extend our analysis to the $K^{(\ast )}{D}_1/K^{(\ast )}{D}_2^{\ast }$ systems, where our results suggest a series of $T_{c\bar{s}}$-type charmed-strange molecular tetraquark candidates. These findings provide a comprehensive picture of the molecular spectrum in the charmed-strange tetraquark sector composed of $S$-wave kaons and (anti-)charmed mesons in the $T$-doublet and can be tested in future experimental studies.

    hep-phhep-exPRD(2026)·3 citations
21. 21*

    Gravitational Waves from Phase Transition in a Supersymmetric Left-Right Model

    Naoyuki Haba🇯🇵 · Yasuhiro Shimizu🇯🇵 · Toshifumi Yamada🇯🇵

    We investigate the cosmological phase transition dynamics in a supersymmetric left-right symmetric model based on the gauge group $SU(3{)}_C\times SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$ that addresses the strong CP problem through extended parity symmetry and doublet-doublet splitting. We compute the finite temperature effective potential including one-loop Coleman-Weinberg corrections, thermal contributions, and daisy resummation to determine whether the $SU(2{)}_R\times U(1{)}_{B-L}\to U(1{)}_Y$ symmetry breaking transition can produce observable gravitational waves. For phenomenologically viable parameters satisfying current LHC constraints, we find that the phase transition is strongly first-order with nucleation temperature $T_n\sim 0.5v_R$, transition strength parameter $\alpha \sim 0.01-0.3$, and inverse duration $\beta /H\sim 100$. The resulting stochastic gravitational wave background peaks at frequencies $f\sim 0.1-1$ Hz with amplitude $h^2{\Omega }_{GW}\sim 10^{-14}-10^{-12}$. We find that there is a parameter region where the gravitational wave spectrum overlaps with DECIGO/BBO sensitivity curves, providing a potentially observable signature connecting the theoretical solution to the strong CP problem with gravitational wave experiments.

    hep-phJHEP(2026)·0 citations
22. 22*

    A radiative seesaw model in a non-invertible selection rule with the assistance of a non-holomorphic modular $A_4$ symmetry

    Shilpa Jangid🇮🇳 · Hiroshi Okada🇨🇳

    We propose a two-loop neutrino mass model where fermionic and bosonic dark matter (DM) candidates are simultaneously connected to the neutrinos. But the fermionic DM candidate is favored compared to the bosonic one due to generating the fermionic DM mass at one-loop level. In order to obtain our desired Lagrangian and Higgs potential, we introduce a $Z_3$ gauging TY non-invertible fusion rule with the assistance of a non-holomorphic modular $A_4$ symmetry. The fusion rule forbids the mass of DM candidate at tree level but its mass is generated at one-loop level where the DM mass term dynamically violates the fusion rule. After that, the neutrino mass matrix is induced at one-loop level where a remnant $Z_2$ symmetry is still remained. The symmetry assures the stability of our DM candidate. The non-holomorphic modular $A_4$ symmetry plays a role in forbidding the interactions between the SM particles and heavier fermions $X_R$ and an isospin singlet inert scalar boson $S_0$ that run in the DM mass loop, in addition to reduction our free parameters that leads to our predictions for lepton sector. We perform ${\chi }^2$ numerical analysis for the lepton masses, mixing angles, and phases, and we show several predictions for NH and IH. Then, we demonstrate our lepton flavor violations, muon anomalous magnetic dipole moment, and the relic density of the DM candidate fixing the best fit point of the lepton sector.

    hep-phPTEP(2026)·17 citations
23. 23*

    A dispersive approach to the CP conserving $K\to \pi {\ell }^{+}{\ell }^{-}$ radiative decays

    Véronique Bernard🇫🇷 · Sébastien Descotes-Genon🇫🇷 · Marc Knecht🇫🇷 · Bachir Moussallam🇫🇷

    We reconsider the constraints on the form factors $W_{+}(s)$ and $W_S(s)$, describing the radiative decay modes $K^{+}\to {\pi }^{+}{\ell }^{+}{\ell }^{-}$ and $K_S\to {\pi }^0{\ell }^{+}{\ell }^{-}$, associated with the general properties of analyticity and unitarity. Starting from the simple consideration of the asymptotic behaviours of the two combinations $2W_{+}(s)-W_S(s)$ and $W_{+}(s)+W_S(s)$, we derive a minimal pair of dispersive representations which involves only two free parameters. An important input for these representations consists of the $K\to 3\pi$ decay amplitudes, for which we use a set of solutions of the Khuri-Treiman equations obtained recently. These solutions provide an extrapolation from the physical $K\to 3\pi$ decay region up to the resonant $K\pi \to \pi \pi$ scattering regions. We show that the experimental energy dependence of $|W_{+}{|}^2$ can be well reproduced and that the sign of $W_{+}$ is unambiguously determined. We also show that the yet unknown $\Delta I=1/2$ part of the $K_S\to {\pi }^{+}{\pi }^{-}{\pi }^0$ amplitude can be determined from the value of $W_{+}(0)+W_S(0)$. The possibility of fixing the sign of $W_S(0)$ using experimental data on both $|W_{+}{|}^2$ and $|W_S{|}^2$ is discussed.

    hep-phJHEP(2026)·2 citations
24. 24*

    High Quality QCD Axion in the Standard Model

    Jie Sheng🇯🇵 · Tsutomu T. Yanagida🇯🇵

    Although the axion is the most compelling solution to the strong CP problem, the ad hoc introduced global Peccei-Quinn symmetry suffers from a severe fine-tuning problem known as the quality problem. In this Letter, we show that the discrete gauge symmetry ${\mathbb{Z}}_4\times {\mathbb{Z}}_3$ motivated from the internal structure of the Standard Model can naturally predict a high-quality axion, leading to a distinct and testable parameter space. Remarkably, this minimal framework simultaneously accounts for neutrino masses, baryon asymmetry, and dark matter.

    hep-phhep-exhep-thPRD(2026)·12 citations
25. 25*

    One-loop QED and Weak Corrections to $\gamma \gamma \to H^{\pm }{H}^{\mp }$ in the Inert Doublet Model

    Hamza Abouabid🇲🇦 · Abdesslam Arhrib🇲🇦 · Jaouad El Falaki🇲🇦 · Bin Gong🇨🇳 · Qi-Shu Yan🇨🇳

    We present a complete one-loop analysis of charged scalar boson pair production in photon-photon collisions, $\gamma \gamma \to H^{\pm }{H}^{\mp }$, within the framework of the Inert Doublet Model (IDM). The calculation is carried out in the on-shell renormalization scheme and incorporates both weak corrections and QED effects, including soft and hard photon radiation. Virtual loop contributions and real emission processes are computed using the Feynman diagrammatic method, ensuring the cancellation of ultraviolet and infrared divergences. To properly account for the Coulomb singularity that arises in the QED sector near threshold, we introduce the resummed cross section based on the Sommerfeld factor. The IDM parameter space is explored under theoretical consistency conditions, collider limits, and dark matter constraints, and three representative scenarios are studied in detail. We find that the magnitude of the quantum corrections is strongly controlled by the absolute value of the trilinear scalar coupling ${\lambda }_{h^0{H}^{+}{H}^{-}}$, which correlates with the charged scalar mass. When all constraints are applied, the weak corrections are typically in the range of $-12\%$ to $-7\%$ at $\sqrt{s}=250$~GeV, and between $-15\%$ and $6\%$ at $\sqrt{s}=500$~GeV. At higher energies, such as $\sqrt{s}=1$~TeV, the corrections can become very large, ranging from about $-20\%$ up to $+60\%$. Our findings highlight the significant role of higher-order effects in photon-photon collisions and establish $\gamma \gamma \to H^{\pm }{H}^{\mp }$ as a promising process to investigate the charged scalar sector of the IDM at future high-energy photon colliders. Several benchmark points are proposed to facilitate future experimental searches.

    hep-phJHEP(2026)·2 citations
26. 26*

    The inclusive Higgs boson cross-section in gluon-gluon fusion in soft-virtual approximation at fourth order in QCD

    Goutam Das🇩🇪 · Sven-Olaf Moch🇩🇪

    We present precise results for the inclusive Higgs boson cross-section in gluon-gluon fusion at the LHC considering state-of-the-art fourth-order results in perturbative QCD arising from the dominant soft and virtual gluon emissions. Utilizing four-loop QCD results for the gluon-form factor, the splitting function and related anomalous dimensions, we study the effects of threshold enhanced soft gluon emissions and estimate their impact on the total cross-section at the fourth order. Our study highlights the role of these higher-order contributions in improving the perturbative convergence and in significantly reducing the renormalization and factorization scale uncertainties. The results provide strong evidence for the perturbative stability and reliability of Higgs boson cross-section predictions at the LHC, thereby reinforcing the robustness of theoretical inputs in precision Higgs phenomenology. We also provide cross-section predictions using a large set of available parton distribution functions and show that, together with the value of the strong coupling ${\alpha }_s(m_Z)$, they cause the largest residual uncertainty for the Higgs boson cross-section in gluon-gluon fusion.

    hep-phSciPost Phys.Comm.Rep.(2026)·2 citations
27. 27*

    Electromagnetic properties of the $D_{s1}^{+}(2460)$, $D_{s1}^{+}(2536)$, and their bottom partners in a molecular configuration

    U. Özdem🇹🇷

    We investigate the electromagnetic properties of the axial-vector molecular states $D^{\ast }K$, $D{K}^{\ast }$, $B^{\ast }K$, and $B{K}^{\ast }$, which are used to model the charmed states $D_{s1}^{+}(2460)$, $D_{s1}^{+}(2536)$, and their bottom partners with quantum numbers $J^P=1^{+}$. To our knowledge, this presents the first comprehensive calculation of the magnetic and quadrupole moments for these specific molecular configurations. Employing the QCD light-cone sum rule method with molecular-type interpolating currents, we compute these moments and perform a detailed flavor decomposition to reveal the internal distribution of the electromagnetic charge and spin. Our results demonstrate that the light up and down quarks dominate the electromagnetic response, with negligible contributions from the heavy quarks. The $D^{\ast }K$ and $B^{\ast }K$ states exhibit negative quadrupole moments and slightly oblate charge distributions, whereas the $D{K}^{\ast }$ and $B{K}^{\ast }$ states possess positive quadrupole moments and prolate distributions, with significant contributions from the strange quark. The predicted moments provide benchmarks for lattice QCD calculations and are testable through their influence on radiative transitions and photo- and electro-production observables at high-luminosity facilities, offering crucial insights into the internal structure and nature of these axial-vector states.

    hep-phhep-exhep-latPRD(2025)·5 citations
28. 28*

    Colour coherence in small collision systems

    Isobel Kolbé🇿🇦 · Chiara Le Roux🇸🇪 · Korinna Zapp🇸🇪

    The observation of collectivity in collisions of small systems has constituted a challenge for the heavy-ion community for over a decade now. The absence of jet quenching in those systems presents an apparent contradiction to the presence of an azimuthal anisotropy of high-$p_{\perp }$ particles. In the present work, we investigate the role of colour coherence in this puzzle. For that, we use the \textsc{Jewel} Monte Carlo model in its latest version, which includes effects of colour coherence in the jet-medium interactions. We then compare the two scenarios, with and without colour coherence, and quantify the effect on hadron and jet $R_{AA}$ as well as on high-$p_{\perp }$ $v_2$. The results indicate that, although coherence effects do account for an increase in $R_{AA}$, they do not affect $v_2$ to the same extent. Using hydrodynamic profiles generated with \textit{Trajectum} we compare O+O and Pb+Pb collisions at the same charged particle multiplicity and find that the nuclear modification factors are the same in both systems despite their different shapes.

    hep-ph1 citation
29. 29*

    Leptonic first-row correlation and unitarity waiting for further JUNO tests

    Zhi-zhong Xing🇨🇳

    We conjecture that there exists a remarkable correlation among the three elements in the first row of the $3\times 3$ lepton flavor mixing matrix $U$: $|U_{e1}^{}{|}^2=2\left(|U_{e2}^{}{|}^2+|U_{e3}^{}{|}^2\right)$, which holds even though $U$ is non-unitary in the canonical seesaw mechanism. This ``first-row correlation" is fully consistent with ${\sin }^2{\theta }_{12}^{}=\left(1-2{\tan }^2{\theta }_{13}^{}\right)/3$ in the unitarity limit of $U$, as supported by the latest JUNO and Daya Bay precision measurements at a confidence level close to $1\sigma$.

    hep-phhep-exnucl-exSci.Bull.(2026)·9 citations
30. 30*

    Probing the Higgs Portal to a Strongly-Interacting Dark Sector at the FCC-ee

    Cesare Cazzaniga🇨🇭 · Annapaola de Cosa🇨🇭 · Felix Kahlhoefer🇩🇪 · Andrea S. Maria🇨🇭 · Roberto Seidita🇨🇭 · Emre Sitti🇨🇭

    This work explores exotic signatures from confining dark sectors that may arise in the $e^{+}{e}^{-}$ collision mode at the Future Circular Collider. Assuming the Higgs boson mediates the interaction between the Standard Model and the dark sector, dark quarks can be produced in $e^{+}{e}^{-}$ collisions. The ensuing strong dynamics may lead to semi-visible jet final states, containing both visible and invisible particles. We investigate semi-visible jets with different fractions of invisible states, and enriched in leptons and photons. When the invisible component is large, selections based on kinematic features, such as the missing energy in the event, already provide good signal-to-background discrimination. For smaller invisible fractions, the reduced missing energy makes these signals more similar to Standard Model events, and we therefore employ a graph neural network jet tagger exploiting differences in jet substructure. This machine learning strategy improves sensitivity and enhances the discovery prospects of Higgs boson-induced semi-visible jets at the Future Circular Collider. Our results show that the proposed strategy can effectively probe a wide parameter space for the models considered, and a variety of signatures, constraining the Higgs boson exotic branching ratios into dark quarks at the permille-level.

    hep-phEPJC(2026)·3 citations
31. 31*

    Automated computation of spin-density matrices and quantum observables for collider physics

    Valentin Durupt🇧🇪 · Fabio Maltoni🇧🇪 · Olivier Mattelaer🇧🇪

    We present a fully automated framework to compute production spin-density matrices for generic collider processes at tree level within \textsc{MadGraph5\_aMC@NLO}. The method assembles helicity amplitudes into event-by-event production matrices. These are written to the LHE file in a compact form, together with run metadata, enabling direct post-processing of quantum observables. The implementation supports bi- and multipartite qubit and qutrit final states, configurable reference frames, and both polarised and unpolarised initial states. A companion, easy-to-extend library provides analysis routines to determine key quantum-information measures and witnesses. These include purity, concurrence, and entanglement of formation for qubits; Peres--Horodecki tests and negativity; spin-polarisation vectors and correlation matrices; $D$-coefficients; and stabiliser-based ``magic'' measures. As a result, multi-particle quantum correlations can be quantified systematically. We validate the implementation against known results for $t\bar{t}$ and $VV$ ($V=W^{\pm },Z$) production in $pp$ and $e^{+}{e}^{-}$ collisions and in heavy-resonance decays. We then consider new applications and study quantum correlations in several LHC final states: $t\bar{t}{W}^{\pm }$, $t{W}^{-}$ vs.\ $t(\bar{t}\to W^{-}\bar{b})$, and $t\bar{t}t$ vs. $t\bar{t}t\bar{t}$.

    hep-phJHEP(2026)·20 citations
32. 32*

    B-Meson Anomalies: Effective Field Theory Meets Machine Learning

    Alejandro Mir🇪🇸 · Jorge Alda🇮🇹 · Siannah Penaranda🇪🇸

    Discrepancies between experimental measurements and Standard Model predictions in $B$-meson decays, especially in lepton flavor universality ratios like $R_{D^{(\ast )}}$, $R_{J/\psi }$ and branching ratios for processes like $B\to K^{+}\nu \bar{\nu }$, suggest possible new physics (NP). In this study, we use an effective field theory framework, assuming NP effects only affect a single generation in the interaction basis, leading to non-universal mixing when rotating to the mass basis. We perform a global fit to the current experimental data, exploring three scenarios characterized by different mixing patterns and constraints. Our analysis finds that the best fit involves mixing between the second and third quark generations, with no lepton sector mixing and independent coefficients for singlet and triplet four-fermion operators. To accurately capture the non-Gaussian nature of the resulting parameter distributions, we use a Machine Learning-based Monte Carlo algorithm, enabling the generation of representative samples that reflect the true underlying distributions. This work highlights the valuable role of Machine Learning in accurately modeling complex parameter distributions in particle physics analyses.

    hep-phPoS(2026)·2 citations
33. 33*

    Higher-order corrections for $t\bar{t}Z$ production

    Nikolaos Kidonakis🇺🇸 · Chris Foster🇺🇸

    We present calculations of higher-order QCD and electroweak (EW) corrections to the associated production of a top-antitop quark pair and a $Z$ boson, i.e. $t\bar{t}Z$ production, in proton collisions. We find that the contributions from soft-gluon corrections are numerically dominant and large. We present approximate NNLO (aNNLO) and approximate N${}^3$LO (aN${}^3$LO) cross sections that include soft corrections on top of the exact NLO QCD result. We also add electroweak corrections through NLO. We compare our aN${}^3$LO QCD + NLO EW theoretical results to measurements of total cross sections from the LHC, and we also calculate top-quark differential distributions in transverse momentum and rapidity.

    hep-phPoS(2025)·1 citation
34. 34*

    Branching ratios for Higgs-mixed scalars at the GeV scale from hadronisation models with conservation laws

    Stefan Gieseke🇩🇪 · Felix Kahlhoefer🇩🇪 · Henry Seebach🇩🇪

    We investigate the decay modes of a CP-even scalar boson $\varphi$ that mixes with the Standard Model Higgs boson, focusing on the mass range between 2 GeV and $2m_{\tau }$. Starting from a higher-order perturbative calculation of the inclusive decays $\varphi \to gg$ and $\varphi \to s\bar{s}$, we employ a hadronisation model to obtain predictions for individual hadronic final states. Our hadronisation model is based on the Herwig cluster model, but incorporates various conservation laws to determine the allowed final states and their respective weights. The model includes two tunable parameters, which we determine using dispersion relation results at $m_{\varphi }=2$ GeV, enabling extrapolation to higher masses. Our predictions show that two-particle hadronic final states like ${\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}$ dominate over ${\mu }^{+}{\mu }^{-}$ for $m_{\varphi }$ near 2 GeV, suggesting promising targets for future experimental searches.

    hep-phhep-exPLB(2026)·2 citations
35. 35*

    Three decades of FCNC studies in 3-3-1 model with right-handed neutrinos: from $Z^{\prime }$-dominance to the alignment limit

    Patricio Escalona🇧🇷 · João Paulo Pinheiro🇨🇳 · Vinícius Oliveira🇵🇹 · A. Doff🇧🇷 · C. A. de S. Pires🇧🇷

    Flavor-changing neutral current (FCNC) processes play a prominent role in the search for physics beyond the Standard Model (SM) due to their sensitivity to new physics at the TeV scale. Meson-antimeson transitions and rare meson decays provide stringent constraints on new physics through precision measurements of observables such as mass differences, CP asymmetries, and branching ratios. Extensions of the SM based on the $\text{SU}(3{)}_C\times \text{SU}(3{)}_L\times \text{U}(1{)}_N$ gauge group offer a compelling framework for flavor physics, as FCNC processes emerge inexorably at tree level due to the non-universal transformations of the quark families. Among its various realizations, the version incorporating right-handed neutrinos (331RHN) is the most phenomenologically viable. This review synthesizes three decades of theoretical developments in FCNC phenomenology within the 331RHN model, from early $Z^{\prime }$-dominated studies to the recent recognition of the decisive role played by the SM-like Higgs boson and the identification of the alignment limit. We demonstrate that viable parameter space spans orders of magnitude, from $m_{Z^{\prime }}\sim$ a few hundred GeV to $\sim 100$ TeV, depending critically on quark mixing parametrizations and scalar alignment configurations, with significant implications for experimental searches at current and future colliders.

    hep-phUniverse(2025)·7 citations
36. 36*

    A Practical Framework for Estimating the Repetition Likelihood of Fast Radio Bursts from Spectral Morphology

    Wan-Peng Sun🇺🇸 · Yong-Kun Zhang🇨🇳 · Ji-Guo Zhang🇺🇸 · Xiaohui Liu🇨🇳 · Yichao Li🇺🇸 · Fu-Wen Zhang🇨🇳 · Wan-Ting Hou🇨🇳 · Jing-Fei Zhang🇺🇸 · Xin Zhang🇺🇸

    The repeating behavior of fast radio bursts (FRBs) is regarded as a key clue to understanding their physical origin, yet reliably distinguishing repeaters from apparent non-repeaters with current observations remains challenging. Here we propose a physically interpretable and practically quantifiable classification framework based on spectral morphology. Using dimensionality reduction, clustering, and feature-importance analysis, we identify the spectral running $r$ and spectral index $\gamma$ as the most critical parameters for distinguishing repeaters from apparent non-repeaters in the CHIME/FRB sample. In the $\gamma$-$r$ space, repeaters preferentially occupy regions with steeper, narrower-band spectra, whereas non-repeaters cluster in flatter, broader-band regions, resulting in a clear density separation. We further construct an empirical probability map in the $\gamma$-$r$ space, showing a clear gradient of repetition likelihood, from $\sim 65\%$ in the high-repetition region to $\sim 5\%$ in the low-repetition region. Combining this with Gaussian Mixture Model posterior analysis, we identify several apparent non-repeaters with high inferred repetition probability, recommending them as priority targets for future monitoring. This framework provides a simple and generalizable tool for assessing repeatability in the CHIME/FRB sample and highlights the diagnostic power of spectral morphology in unveiling FRB origins.

    ↳ astro-ph.HEastro-ph.IMgr-qchep-phApJ(2026)·8 citations
37. 37*

    Localization mechanism of the Kalb-Ramond field on brane with codimension-two

    Yong-Tao Lu🇨🇳 · Heng Guo🇨🇳 · Qun Wei🇨🇳 · Bing Wei

    The $2$-form Kalb-Ramond (KR) field, together with the metric tensor and dilaton, arises as one of the massless excitation mode of a closed string. Subsequently, this field plays an important role in both string theory and field theory. In this paper, we investigate the localization of the KR field on the brane with codimension-2. A general Kaluza-Klein (KK) decomposition is adopted, wherein the six-dimensional KR field is expanded into one four-dimensional (4D) KR field, two 4D vector fields, and one 4D scalar field. Then, for the case of the extra dimensions ${\mathcal{R}}_1\times {\mathcal{R}}_1$, only the 4D scalar field can be localized on the brane. In contrast, for the case of extra dimensions ${\mathcal{R}}_1\times {\mathcal{S}}_1$, one 4D vector field and the 4D scalar field can be localized on the brane at the same time. In both cases, the mass of the 4D scalar field remains zero. Next, we examine the localization of the KR field within a specific six-dimensional brane model with extra dimensions ${\mathcal{R}}_1\times {\mathcal{S}}_1$. By introducing the background scalar coupling, we show that the 4D KR field, along with the other three 4D fields, can be localized on the brane under the condition of the coupling parameter $t>v^2/12$. Additionally in this case, for both the 4D KR field and the one 4D vector field which acquires its mass from the non-compact extra dimension, the resonant KK modes could exist near the origin of this extra dimension.

    ↳ hep-thhep-ph0 citations
38. 38*

    The deep-MOND limit -- a study in Primary vs secondary predictions

    Mordehai Milgrom🇮🇱

    In default of a fundamental MOND theory -- a FUNDAMOND -- I advocate that, alongside searching for one, we should try to identify predictions that follow from wide classes of MOND theories, if not necessarily from all. In particular, predictions that follow from only the basic tenets of MOND -- ``primary predictions'' -- are shared by all MOND theories, and are especially valuable. Such predictions permit us to test the MOND paradigm itself, or at least large parts of it, without yet having a FUNDAMOND. Concentrating on the deep-MOND limit, I discuss examples of either type of predictions. For some examples of primary predictions, I demonstrate how they follow from the basic tenets (which I first formulate). I emphasize that even predictions that pertain to the deep-MOND limit - namely, those that concern gravitating systems that have low accelerations everywhere -- require the full set of MOND tenets, including the existence of a Newtonian limit close to the deep-MOND regime. This is because Newtonian dynamics is a unique theory that all MOND theories must tend to in the limit of high accelerations, and it strongly constrains aspects of the deep-MOND regime, if the transition between the limits is fast enough, which is one of the MOND tenets.

    ↳ gr-qcastro-ph.GAhep-ph0 citations
39. 39*

    Search for a hypothetical gauge boson and dark photons in charmonium transitions

    BESIII Collaboration: M. Ablikim · M. N. Achasov · P. Adlarson · X. C. Ai · R. Aliberti · A. Amoroso · Q. An · Y. Bai · O. Bakina · Y. Ban · H.-R. Bao · V. Batozskaya and 689 other authors

    We report a direct search for a new gauge boson, $X$, with a mass of $17\text{MeV}/c^2$, which could explain the anomalous excess of $e^{+}{e}^{-}$ pairs observed in the ${}^8\text{Be}$ nuclear transitions. The search is conducted in the charmonium decays ${\chi }_{cJ}\to XJ/\psi (J=0,1,2)$ via the radiative transition $\psi (3686)\to \gamma {\chi }_{cJ}$ using $\left(2712.4\pm 14.3\right)\times 10^6$ $\psi (3686)$ events collected with the BESIII detector at the BEPCII collider. No significant signal is observed, and the updated upper limit on the coupling strength of charm quark and the new gauge boson, ${ϵ}_c$, is set to be $|{ϵ}_c|<1.2\times 10^{-2}$ at $90\%$ confidence level. We also report new constraints on the mixing strength $ϵ$ between the Standard Model photon and dark photon ${\gamma }^{\prime }$ in the mass range from $5\text{MeV}/c^2$ to $300\text{MeV}/c^2$. The upper limits at $90\%$ confidence level vary within $(2.5-17.5)\times 10^{-3}$ depending on the ${\gamma }^{\prime }$ mass.

    ↳ hep-exhep-phPRD(2026)·6 citations
40. 40*

    Short-Range Correlations and Transverse Response Enhancement from Meson-Exchange Currents

    P.R. Casale🇪🇸 · J.E. Amaro🇪🇸

    We investigate the role of short-range correlations (SRC) in the transverse nuclear response within the quasielastic peak region, focusing on the 1p1h channel. The calculation is performed in nuclear matter by solving the Bethe-Goldstone equation with the realistic Granada 2013 nucleon-nucleon potential, including both one-body and two-body meson-exchange currents (MEC) of seagull, pion-in-flight, and $\Delta$ types. We find that MEC produce a sizable enhancement of the transverse response in the 1p1h channel when acting on correlated nucleon pairs with high-momentum components generated by SRC. This contrasts with the uncorrelated case, where MEC, dominated by the $\Delta$ current, can even yield a negative effect. The results are consistent with previous findings based on the correlated basis function approach, supporting the interpretation that SRC play a central role in the transverse response enhancement from MEC.

    ↳ nucl-thhep-phJ.Phys.G(2025)·2 citations
41. 41*

    Axion inflation in the regime of homogeneous backreaction

    Matteo Barbon🇮🇹 · Nadir Ijaz🇮🇹 · Marco Peloso🇮🇹

    We investigate the Stochastic Gravitational Wave Background (SGWB) produced in models of axion inflation coupled to gauge fields. Achieving a detectable signal at Pulsar Timing Array, astrometry, or interferometer frequencies requires a sufficiently strong amplification of the gauge fields, at a level that induces significant backreaction on the inflaton background dynamics. Numerical studies based on the approximation of homogeneous backreaction (i.e., neglecting inhomogeneities of the inflaton field) exhibit oscillations in the inflaton velocity, with corresponding peaks in the SGWB spectrum. The most recent lattice simulations have questioned the validity of this regime, showing examples characterized by a rapid increase in the inflaton gradient energy and the breakdown of homogeneous backreaction. We compute this energy density perturbatively within the assumption of homogeneous backreaction, obtaining examples with a detectable SGWB and with an inflaton gradient energy that remains subdominant to the inflaton zero-mode kinetic energy throughout inflation.

    ↳ astro-ph.COhep-phhep-thJCAP(2026)·16 citations
42. 42*

    The Dark Matters at ICRC 2025

    Milena Crnogorčević🇸🇪

    The dark matter track at ICRC~2025 showed a field in transition. Direct detection has entered the \emph{neutrino-floor era}, with XENONnT and PandaX-4T now limited by Solar neutrinos. Indirect searches have become truly \emph{multimessenger}, combining $\gamma$-rays, neutrinos, cosmic rays, and radio data under unified likelihoods and shared systematics. Non-WIMP candidates -- axions, sub-GeV particles, primordial black holes, macroscopic relics -- are becoming central. Across all fronts, progress depends as much on new detectors as on the coherence of shared data, methods, and analysis frameworks. Here, I distill the main experimental and conceptual shifts behind these trends, noting how assumptions have evolved since ICRC~2023 and where the next decisive advances are likely to come.

    ↳ astro-ph.HEhep-exhep-phPoS(2025)·0 citations
43. 43*

    Electromagnetic form factors and structure of the $T_{bb}$ tetraquark from lattice QCD

    Ivan Vujmilovic🇸🇮 · Sara Collins🇩🇪 · Luka Leskovec🇸🇮 · Sasa Prelovsek🇸🇮

    We present the first lattice QCD determination of the electromagnetic form factors of the exotic tetraquark $T_{bb}(bb\bar{u}\bar{d})$ with quantum numbers $I(J^P)=0(1^{+})$. The extracted form factors encode information about its internal structure, including the charge distribution and the magnetic dipole moments, determined separately for the light and heavy quarks. Our results provide evidence in favor of it being a bound state consisting of a compact heavy diquark $[bb]$ in a color-antitriplet with spin one, and a light antidiquark $[\bar{u}\bar{d}]$ in a color-triplet with spin zero. The charge radius of $T_{bb}$ is found to be significantly smaller than the combined charge radii of $B$ and $B^{\ast }$ mesons. These two comprise the lowest-lying threshold $B{B}^{\ast }$ in the channel we are considering, and their electric charge form factors are also determined. The computations were performed on a single CLS ensemble with $N_f=2+1$ dynamical quarks and a lattice spacing of approximately $a\approx 0.064\mathrm{fm}$ at the pion mass $m_{\pi }\approx 290\mathrm{MeV}$.

    ↳ hep-lathep-phPRL(2026)·11 citations
44. 44*

    Production of gravitational waves by inflationary transitions in aligned natural inflation

    Federico Greco🇮🇹

    The original axion natural inflation model predicts a tensor-to-scalar ratio exceeding experimental limits. Conversely, in aligned axion inflation, inflation can proceed along trajectories emerging from near a saddle point of the two-field potential and ending through an instability in the orthogonal direction. Such solutions satisfy present observational limits and will be tested by future CMB experiments. Previous studies have suggested the possibility of two distinct inflationary stages separated by a transition characterized by rapid oscillations of the fields. In this work, we demonstrate that the existence of these two stages is a generic feature of the model. We explore a possible phenomenological signature of the transition when a U(1) gauge field is coupled to the axions, namely, the production of gravitational waves (GWs) sourced by gauge quanta generated during the transition. This mechanism produces a feature similar to those seen in spectator axion models or axion inflation with appropriate potentials, i.e. a strongly scale-dependent power spectrum. The scale at which the GW spectrum is produced is determined by the duration of the second inflationary phase. Consequently, the spectrum may peak at different frequencies, potentially detectable by future GW experiments.

    ↳ astro-ph.COhep-phhep-thJCAP(2026)·3 citations
45. 45*

    Prospects for Measuring $CP$-Violation in $B_s^0\to \varphi {\mu }^{+}{\mu }^{-}$ via Time-Dependent Angular Analysis

    Sebastian Schmitt🇺🇸 · Amr Elmarassy🇺🇸 · Michele Atzeni🇺🇸 · Eluned Smith🇺🇸

    This work investigates the prospects for performing a time-dependent angular analysis of $B_s^0\to \varphi {\mu }^{+}{\mu }^{-}$ decays at hadron colliders, and introduces new optimised angular observables associated with $B_s^0$-mixing in the decay rate. The time-dependent normalised decay rate and corresponding probability density function is presented both for when the flavour of the $B_s^0$ meson at production is tagged and when it is untagged. The normalised angular terms linked to $B_s^0$-mixing in the tagged (untagged) case are denoted ${\mathcal{Z}}_i$ (${\mathcal{H}}_i$), and their optimised counterparts as $Q_i$ (${\mathcal{M}}_i$). The expected sensitivities of these observables at the end of Run 3, Run 4, and Run 5 of the LHC are determined using pseudoexperiments generated with a decay-time resolution, background level, and signal yield similar to those reported by the LHCb collaboration. It is found that all observables can be extracted with Run 3 statistics, and that the ${\mathcal{H}}_i$ and ${\mathcal{Z}}_i$ observables have similar sensitivity, despite the former being suppressed by mixing terms. Moreover, the angular observables only accessible via flavour tagging, such as the equivalent of $P_5^{\prime }$ in the $B_s^0$ system, are found to exhibit sensitivities comparable to current measurements in $B^0\to K^{\ast 0}{\mu }^{+}{\mu }^{-}$ decays once Run 5 datasets are available. Fits to the observables to extract the Wilson coefficients show a significant increase in precision when either the observables accessible via time-dependent analysis, or flavour tagging, are included. A marked increase in sensitivity to $CP$-violating short-distance effects is observed for a subset of the new optimised $M_i$ and $Q_i$ observables.

    ↳ hep-exhep-phPRD(2026)·0 citations
46. 46*

    Exorcising ghosts with gravitational waves: cases of ghostful and ghost-free fourth-order gravity

    Gaetano Lambiase🇮🇹 · Shinji Mukohyama🇯🇵 · Tanmay Kumar Poddar🇮🇹 · Anna Chiara Rescigno🇮🇹

    General Relativity (GR) is an effective field theory valid in the infrared regime. Quadratic curvature extensions intended to probe ultraviolet physics generically propagate a massive spin-$2$ ghost and are therefore non-unitary. One route to remove ghost is by enlarging the geometric sector (torsion, non-metricity). We investigate the infrared phenomenology of both the standard (ghostful) and ghost-free fourth-order gravity theories by computing Gravitational Wave (GW) emission and confronting the results with observations such as the orbital-period decay of quasi-stable binaries such as PSR B1913+16 and PSR J1738+0333 and the chirp-mass evolution of GW170817. In the ghostful theory, besides the theoretical inconsistency due to non-unitarity, there are also phenomenological problems: the massless spin-$2$ GW flux cancels the combined GW fluxes of the massive spin-$2$ ghost and massive spin-$0$ scalar in the vanishing-mass limit, so the GR quadrupole formula is not recovered at the leading order. As a result, we obtain the GW constraint on the ghostful theory as $m\gtrsim 10^{-11}\mathrm{eV}$, where $m$ is the mass of the massive modes. By contrast, the ghost-free theory smoothly reproduces the Newtonian potential and GR quadrupole formulae when the two coupling constants ${\alpha }_1$ and ${\alpha }_2$ vanish, independently of the mass $m$. Therefore, GW observations put mass-dependent upper bounds on the size of the coupling constants. For example, if we assume ${\alpha }_1\simeq {\alpha }_2$ for simplicity, then we obtain ${\alpha }_{1,2}\lesssim 4.2\times 10^{83}$ for $m\sim 3\times 10^{-16}\mathrm{eV}$ and ${\alpha }_{1,2}\lesssim 1.3\times 10^{75}$ for $m\sim 10^{-11}\mathrm{eV}$. To our knowledge, these are the first astrophysical-scale bounds reported for ghostful and ghost-free fourth-order gravity.

    ↳ gr-qcastro-ph.COhep-ph6 citations
47. 47*

    Holographic Systems out of Equilibrium: From Flavor Branes to SYK Wormholes

    Martí Berenguer Mimó🇪🇸

    This thesis studies the non-equilibrium dynamics of strongly coupled quantum systems within the framework of the AdS/CFT correspondence, with particular emphasis on periodically driven (Floquet) systems. The first part focuses on top-down holographic constructions based on D3/D5 and D3/D7 brane intersections subjected to time-dependent external fields. In the D3/D5 system at finite temperature, we analyze the response to a rotating electric field and uncover a rich non-equilibrium phase structure containing conductive and insulating phases, vector meson Floquet condensates, and Floquet suppression points. In the D3/D7 setup, we study the effects of helical magnetic fields on chiral symmetry breaking, showing that sufficiently helical magnetc fields can restore chiral symmetry. The second part examines the periodically driven Maldacena-Qi model, a two-site extension of the SYK model dual to a traversable wormhole. We identify resonances that enhance or suppress the wormhole traversability and find evidence that the unstable region of the phase diagram can be dynamically accessed. We use our driving protocols to access this region and compute its Lyapunov exponent. Overall, this thesis advances the use of the holographic techniques to probe non-equilibrium steady states and real-time dynamics in strongly coupled quantum systems.

    ↳ hep-thgr-qchep-ph0 citations
48. 48*

    Using Strong Lensing to Detect Subhalos with Steep Inner Density Profiles

    Kassidy E. Kollmann🇺🇸 · James W. Nightingale · Mariangela Lisanti🇺🇸 · Andrew Robertson🇺🇸 · Oren Slone🇮🇱

    The inner region of a subhalo's density distribution is particularly sensitive to dark matter microphysics, with alternative dark matter models leading to both cored and steeply-rising inner density profiles. This work investigates how the lensing signature and detectability of dark matter subhalos in mock HST-, Euclid-, and JWST-like strong lensing observations depend on the subhalo's radial density profile, especially with regards to the inner power-law slope, $\beta$. We demonstrate that the minimum subhalo mass detectable along the Einstein ring of a system is strongly dependent on $\beta$. In particular, we show that subhalos with $\beta =2.2$ can be detected down to masses over an order-of-magnitude lower than their Navarro-Frenk-White (NFW) counterparts with $\beta =1$. Importantly, we find that the detectability of subhalos with steep inner profiles is minimally affected by increasing the complexity of the main lens galaxy's mass model. This is a notable characteristic of these subhalos, as those with NFW or shallower profiles become essentially undetectable when multipole perturbations are added to the lens model. The results of this work highlight how the underlying dark matter physics can significantly impact the expected number of subhalo detections from strong gravitational lensing observations. This is important for testing Cold Dark Matter against alternative models, such as Self-Interacting Dark Matter, that predict a diverse range of subhalo inner density profiles.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2026)·5 citations
49. 49*

    Resonance phenomena in vortex-antivortex collisions

    Maximilian Bachmaier🇩🇪 · Andrzej Wereszczynski🇵🇱

    In this work, we provide a full map of scattering scenarios between a Nielsen-Olesen vortex and antivortex. Importantly, in the deep type II regime, such a collision reveals a chaotic pattern in the final state formation with bounce windows immersed into annihilation regions. This structure is due to the energy transfer mechanism triggered by a quasinormal mode, specifically the Feshbach resonant mode, hosted by the vortex.

    ↳ hep-thhep-phnlin.PSPLB(2026)·11 citations
50. 50*

    Scalar fields around black hole binaries in LIGO-Virgo-KAGRA

    Soumen Roy🇧🇪 · Rodrigo Vicente🇳🇱 · Josu C. Aurrekoetxea🇺🇸 · Katy Clough🇬🇧 · Pedro G. Ferreira🇬🇧

    Light scalar particles arise naturally in many extensions of the Standard Model and are compelling dark-matter candidates. Gravitational interactions near black holes can trigger the growth of dense scalar configurations that, if sustained during inspiral, alter binary dynamics and imprint signatures on gravitational-wave signals. Detecting such effects would provide a novel probe of fundamental physics and dark matter. Here we develop a semi-analytic waveform model for binaries in scalar environments, validate it against numerical relativity simulations, and apply it in a Bayesian analysis of the LIGO-Virgo-KAGRA catalog. We obtain physically meaningful upper limits on scalar densities around most compact binaries. For GW190728 and GW190814, vacuum lies outside the $95\%$ credible region. When including superradiance priors, GW190728 shows tentative evidence for a scalar environment with a Bayes factor of $\ln {\mathrm{B}}_{\mathrm{vac}}^{\mathrm{env}}\approx 3.5$, consistent with a light scalar of mass $\sim 10^{-12}\mathrm{eV}$.

    ↳ gr-qcastro-ph.COastro-ph.HEhep-phPRL(2026)·22 citations
51. 51*

    Supersymmetry searches in CMS Run 2: A complete review

    Sezen Sekmen🇰🇷

    The Run 2 data-taking period of the CERN Large Hadron Collider during years 2015-2018 provided about 140 fb${}^{-1}$ of proton-proton collisions at 13 TeV, offering an unprecedented opportunity to explore supersymmetry (SUSY) across a wide range of experimental signatures. CMS responded with a broad and diverse search program, carrying out dozens of analyses that probed a multitude of final states and systematically explored different regions of the SUSY parameter space. No significant deviations from standard model predictions were observed, and the results were used for constraining the SUSY landscape. In this review, I provide a comprehensive account of the CMS Run 2 SUSY program, covering its strategy, targeted models, and analysis methods. I then present the full set of searches and conclude with their combined impact through simplified model and phenomenological MSSM interpretations.

    ↳ hep-exhep-phHiHEP(2025)·7 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.