Tue·Dec 9, 2025Tuesday·December 9, 2025

1. 01*

   Portals to New Physics: The W-Quark Portal

   Linda M. Carpenter🇺🇸 · Katherine Schwind🇺🇸 · Taylor Murphy🇺🇸

   We explore new EFT operators where single new exotic states interact with the Standard Model through an asymmetric Standard Model portal with couplings to at least one quark and one W boson. Effective operators up to dimension 6 are considered, and we specify SM charges of all new states accessible through this portal. We explore our interactions by detailing possible collider production processes at e-p and p-p colliders. Finally, we study the LHC production of a new weak-quadruplet SU(3) fundamental fermion which can be singly produced in association with a SM quark through W-quark portal processes.

   hep-ph1 citation
2. 02*

   Inferring the breakdown scales of the chiral expansions for $g_A$ and $m_N$

   Andreas Ekström🇸🇪 · Daniel R. Phillips🇺🇸 · Lucas Platter🇺🇸 · Matthias R. Schindler🇺🇸

   We apply Bayesian inference to the order-by-order chiral perturbation theory ($\chi$PT) expansions for the axial-vector coupling constant $g_A$ and the nucleon mass m_N, and thereby infer the scales at which $\chi$PT breaks down for these two observables. Using a pointwise Bayesian analysis, we find that the inferred breakdown scales are notably different for the two observables. For the chiral expansion of $g_A$, we obtain $251_{-50}^{+20}$ MeV and $211_{-30}^{+20}$ MeV using two distinct sets of low-energy constants, while for the chiral expansion of $m_N$ we infer a significantly larger breakdown scale of $491_{-90}^{+60}$ MeV.

   hep-phnucl-thPLB(2026)·3 citations
3. 03*

   Photon emission from weakly magnetized neutral pions

   Xinyang Wang🇨🇳 · Fan Lin🇨🇳 · Igor Shovkovy🇺🇸

   Using a hadronic framework, we derive an explicit expression for photon production from neutral pions in a weak background magnetic field. Our calculation is built on the proton triangle diagram with an effective Yukawa ${\pi }^0$-proton coupling, offering an alternative to quark-level descriptions that is advantageous when the magnetic length greatly exceeds the proton size. Corrections to the pion decay constant are computed up to second order in the magnetic-field strength, revealing that the field generally suppresses the decay rate. Quantitatively, however, the effect remains modest even for fields as strong as $|eB|\simeq m_{\pi }^2$. The differential photon emission rate exhibits anisotropy, with the strongest suppression occurring when the pion momentum is perpendicular to the magnetic field. Overall, the modification of the ${\pi }^0\to \gamma \gamma$ rate is parametrically small, scaling as $|eB{|}^2/m_P^4$, where $m_P$ is the proton mass. While the magnetic-field-induced anisotropy is conceptually interesting in principle, it is likely too small to be resolved in present heavy-ion measurements.

   hep-phnucl-thPRD(2026)·1 citation
4. 04*

   The impact of inclusive electron ion collider data on the strong coupling determination in a global PDF fit

   L. A. Harland-Lang🇬🇧 · T. Cridge🇧🇪 · P. Newman🇬🇧 · R.S. Thorne🇬🇧 · K. Wichmann🇩🇪

   We present a study of the impact of data from the upcoming Electron Ion Collider (EIC) on the determination of the strong coupling within the context of the global MSHT fitting framework. To achieve this, we generate EIC electron-proton scattering pseudodata according to both conservative and optimistic experimental uncertainty projections and perform a simultaneous fit to obtain the proton PDFs and the value of the strong coupling. In the conservative case the impact is found to be moderate, but non-negligible, while in the optimistic case it is observed to be rather significant. These results therefore underline the promising potential for the EIC in the determination of the strong coupling. We in addition explore the impact of any potential tensions between the EIC data and the rest of the data in the global fit by injecting explicit inconsistencies into the pseudodata generation. This can lead to a noticeable bias in the extracted value of the strong coupling, highlighting the importance of accounting for all sources of theoretical uncertainty in the fit as well as the relevance of an enlarged, conservative, error definition in the determination of the strong coupling.

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

   On the efficiency of parameter space exploration: A scotogenic case study

   Ugo de Noyers🇫🇷 · Mathis Dubau🇫🇷 · Björn Herrmann🇫🇷 · Olivier Arnaez🇫🇷

   A common problem in beyond Standard Model phenomenology is the exploration of a multi-dimensional parameter space in view of a large number of constraints. We study and compare two methods applicable to this challenge, namely a Markov Chain Monte Carlo scan (MCMC) and a Deep Neural Network (DNN). We illustrate both methods via their application to different scotogenic frameworks, allowing to extend the Standard Model to include viable dark matter candidates while generating neutrino mass terms at the one-loop level. Our studies allow us to compare the two employed methods, both at the level of phenomenology and at the level of computing effort. We find that, while phenomenologically speaking both methods deliver compatible conclusions, the obtained datasets feature differences at the detail level in the distributions of observables, e.g. the dark matter mass.

   hep-ph1 citation
6. 06*

   Spontaneous Leptogenesis in Type I Seesaw

   Eung Jin Chun🇰🇷 · Hyun Min Lee🇰🇷 · Jun-Ho Song🇰🇷

   Type-I seesaw models with a spontaneously broken $B-L$ symmetry provide a natural framework for spontaneous leptogenesis driven by a Majoron. The kinetic background of the Majoron acts as a CP-violating source, generating a lepton asymmetry both through the decay of right-handed neutrinos and through equilibration via inverse-decay processes. We construct the Boltzmann equations in a fully consistent manner, incorporating both effects, to enable a quantitative analysis. When the neutrino Yukawa coupling is large enough to maintain $B-L$ violating interactions in thermal equilibrium, the resulting asymmetry closely tracks its equilibrium value. In contrast, when this condition is not satisfied, a nontrivial interplay emerges between decay and inverse-decay dynamics, determined by the Yukawa coupling strength and the initial abundance of right-handed neutrinos.

   hep-phPRD(2026)·9 citations
7. 07*

   Constraining meV Axion Dark Matter with ALMA Observations of the Galactic Center Magnetar SGR 1745-2900

   Javier De Miguel🇪🇸 · Evanthia Hatziminaoglou🇪🇸 · Frédéric Poidevin🇪🇸 · Nanda Rea🇪🇸 · Daniel L. Walker🇬🇧 · Davide De Grandis🇪🇸 · Jaime Prieto-Polo🇪🇸

   We report a mm-wave search for axion dark matter from SGR 1745-2900, based on 4.8 h of ALMA observations. No candidate features are found between 133.99-135.78, 135.91-137.70, 145.99-147.78, and 147.99-149.78~GHz, corresponding to 0.55-0.62 meV. Interpreting this null result within a state-of-the-art stellar framework, we derive sensitivity to the axion-photon coupling at the level of $g_{\gamma }\gtrsim 2\times 10^{-11}$ GeV${}^{-1}$ under a standard Navarro-Frenk-White profile; down to $g_{\gamma }\gtrsim 2\times 10^{-13}$ GeV${}^{-1}$ upon accounting for a dense dark-matter spike around Sagittarius A*, probing the quantum chromodynamics axion parameter space.

   hep-phastro-ph.COastro-ph.HEastro-ph.SR+1PLB(2026)·2 citations
8. 08*

   Axial-vector molecules ${\rm Y}{B}_c^{-}$ and ${\eta }_b{B}_c^{\ast -}$

   S. S. Agaev🇦🇿 · K. Azizi🇮🇷 · H. Sundu🇹🇷

   Axial-vector hadronic molecules ${\mathcal{M}}_{\mathrm{AV}}={\rm Y}{B}_c^{-}$ and ${\tilde{\mathcal{M}}}_{\mathrm{AV}}={\eta }_b{B}_c^{\ast -}$ with the quark content $bb\overline{b}\overline{c}$ are studied using QCD sum rule method. The spectroscopic parameters of these molecules are computed in the context of the two-point sum rule method. Predictions for their masses are identical to each other and confirm that they are structures unstable against dissociations to ordinary heavy mesons. We evaluate the width of the state ${\mathcal{M}}_{\mathrm{AV}}$ and assume that it is equal to that of ${\tilde{\mathcal{M}}}_{\mathrm{AV}}$. To this end, we explore its dominant decay channels ${\mathcal{M}}_{\mathrm{AV}}\to {\rm Y}{B}_c^{-}$ and ${\mathcal{M}}_{\mathrm{AV}}\to {\eta }_b{B}_c^{\ast -}$. There also are subleading modes of ${\mathcal{M}}_{\mathrm{AV}}$ generated due to annihilation of $\overline{b}b$ quarks. We consider decays of the molecule ${\mathcal{M}}_{\mathrm{AV}}$ to pairs of the mesons $B^{\ast -}{\overline{D}}^0$, ${\overline{B}}^{\ast 0}{D}^{-}$, $B^{-}{\overline{D}}^{\ast 0}$, ${\overline{B}}^0{D}^{\ast -}$, ${\overline{B}}_s^{\ast 0}{D}_s^{-}$, and ${\overline{B}}_s^0{D}_s^{\ast -}$. To find strong couplings at the ${\mathcal{M}}_{\mathrm{AV}}$-meson-meson vertices which determine the partial widths of these processes, we apply QCD three-point sum rule approach. The mass $m=(15800\pm 90)\mathrm{MeV}$ and width $\Gamma [{\mathcal{M}}_{\mathrm{AV}}]=(114\pm 17)\mathrm{MeV}$ of the molecule ${\mathcal{M}}_{\mathrm{AV}}$ are useful for experimental studies of fully heavy molecular structures at ongoing and planning experiments.

   hep-phhep-exhep-latEPJA(2026)·7 citations
9. 09*

   Determination of proton electromagnetic form factors from DVCS measurements

   The MMGPDs Collaboration · Anoushiravan Moradi · Muhammad Goharipour · H. Fatehi · K. Azizi

   We present a detailed analysis of the proton electromagnetic form factors (FFs) using exclusive photon leptoproduction (EP) data in kinematic regions where the Beth-Heitler (BH) contribution dominates the deeply virtual Compton scattering (DVCS) cross section By exploiting the sensitivity of the BH amplitude to the Dirac and Pauli FFs, we extract $F_1(t)$, $F_2(t)$, and the corresponding Sachs FFs within several fitting scenarios based on dipole and $P$-pole parametrizations, and evaluate the charge and magnetic radii of the proton. In this fitting scenario, we show that EP measurements in the range $0.11<|t|<0.45{\mathrm{GeV}}^2$ can provide constraints on $F_1(t)$, while offering limited sensitivity to $F_2(t)$. The extracted charge radius values tend to be smaller than those obtained from traditional elastic electron-proton scattering measurements and are consistent, within uncertainties, with recent hig-precision PRad results. These findings indicate that EP measurements, especially when covering smaller values of $|t|$, can serve as a complementary tool for determining the proton electromagnetic structure and may contribute to ongoing efforts to better understand the proton charge radius.The methodology developed here provides a framework for future combined analyses of EP and elastic electron-proton scattering data which enables a unified determination of the nucleon FFs.

   hep-phhep-exPRD(2026)·3 citations
10. 10*

    Probing anomalous $W^{-}{W}^{+}\gamma /Z$ couplings in the SMEFT with $e^{-}{e}^{+}\to W^{-}{W}^{+}\to 4j/{\ell }^{-}{\ell }^{+}\text{slashed}E$ channel

    Amir Subba🇮🇳 · Ritesh K. Singh🇮🇳

    We investigate anomalous charged triple gauge boson couplings induced by $SU(2{)}_L\times U(1{)}_Y$ gauge-invariant dimension-6 operators in the HISZ basis through the processes $e^{-}{e}^{+}\to 4j$ and $e^{-}{e}^{+}\to {\ell }^{-}{\ell }^{+}+\text{missing energy}$ at $\sqrt{s}=250$GeV with longitudinally polarized beams. The analysis includes three CP-even operators $(O_{WWW},O_W,O_B)$ and two CP-odd operators $({\tilde{O}}_{WWW},{\tilde{O}}_W)$, which parameterize deviations in the $W^{-}{W}^{+}\gamma /Z$ vertex. All leading-order contributions are included, including interference between $W^{-}{W}^{+}$ production and non-resonant amplitudes. In the $e^{-}{e}^{+}\to 4j$ channel, $W^{-}{W}^{+}$ candidates are selected using boosted decision trees. The $W$-boson charges are reconstructed using a jet-charge observable, and jet flavors from $W$ decays are identified with a dedicated classifier, enabling measurements of vector polarization and correlation asymmetries. In the $e^{-}{e}^{+}\to {\ell }^{-}{\ell }^{+}+\text{missing energy}$ channel, events are selected with cuts on lepton transverse momentum and dilepton mass, and the two neutrino momenta are reconstructed using neural-network regression. Combining total cross sections with spin asymmetries allows constraints on anomalous gauge couplings. The fully hadronic channel provides the strongest sensitivity to $O_B$ and ${\tilde{O}}_W$, while the semi-leptonic channel yields tighter limits on $O_{WWW}$, $O_W$, and ${\tilde{O}}_{WWW}$. The fully leptonic channel adds complementary sensitivity. Finally, we derive marginalized limits on all five operators using a Markov Chain Monte Carlo analysis for several choices of systematic uncertainties and integrated luminosities.

    hep-ph1 citation
11. 11*

    Nucleon 3D intrinsic spin structure from the weak-neutral axial-vector form factors

    Yi Chen🇨🇳

    Relativistic 3D weak-neutral axial-vector four-current and spin distributions inside a nucleon (or a general spin-$\frac{1}{2}$ hadron) including three weak-neutral axial-vector form factors are investigated for the first time. We clarify that the relativistic 3D axial charge distribution in the Breit frame is completely described by the induced pseudotensor form factor $G_T^Z(Q^2)$ rather than by the axial form factor $G_A^Z(Q^2)$. We demonstrate that $R_A\equiv \sqrt{\frac{-6}{G_A^Z(0)}\frac{\text{d}{G}_A^Z(Q^2)}{\text{d}{Q}^2}{|}_{Q^2=0}}$ can not be interpreted as the physically meaningful 3D root-mean-square axial radius of a spin-$\frac{1}{2}$ hadron. The genuine axial radius for any spin-$\frac{1}{2}$ hadron in fact does not exist. We also show that the relativistic 3D weak-neutral spin radius $r_{\text{spin}}=\sqrt{⟨r_{\text{spin}}^2⟩}$, with $⟨r_{\text{spin}}^2⟩\equiv R_A^2+\frac{1}{4M^2}\left[1+\frac{2G_P^Z(0)}{G_A^Z(0)}\right]$ based on the relativistic and intrinsic 3D weak-neutral spin distribution in the Breit frame, is a physically meaningful radius that can be unambiguously defined for the nucleon, which provides an additional key motivation for the further determination of the induced pseudoscalar form factor $G_P^Z(Q^2)$. Numerically, we find that $R_A\approx 0.6510\text{fm}$, $r_{\text{spin}}\approx 2.1054\text{fm}$ and ${\overline{r}}_{\text{spin}}\equiv r_{\text{spin}}/3\approx 0.7018\text{fm}$. For future experimental measurements of $G_A^Z(Q^2)$ and $G_T^Z(Q^2)$, we also derive the full tree-level unpolarized differential cross sections for neutrino-proton and antineutrino-proton elastic scattering in the lab frame, in hoping to provide a complementary and new perspective to unveil the nucleon spin structure by using (anti)neutrino-based facilities.

    hep-phhep-thnucl-th1 citation
12. 12*

    A note on instantons, $\theta$-dependence and strong CP

    Valentin V. Khoze🇬🇧

    I review the standard instanton framework for determining the $\theta$-dependence of instanton-dominated correlation functions in QCD. I then contrast these well-established semiclassical results with the recent assertion of [1,2], that $\theta$-phases are absent and that strong interactions preserve CP for all values of $\theta$. In all scenarios considered, the $\theta$-dependence is shown to be intrinsically non-trivial, being governed either by instantons in the weak-coupling regime or by alternative, non-perturbative considerations when the theory is strongly coupled.

    hep-phhep-thJHEP(2026)·15 citations
13. 13*

    Solving the Inverse Source Problem in Femtoscopy with a Toy Model

    Ao-Sheng Xiong🇨🇳 · Qi-Wei Yuan🇨🇳 · Ming-Zhu Liu🇨🇳 · Fu-Sheng Yu🇨🇳 · Zhi-Wei Liu🇨🇳 · Li-Sheng Geng🇨🇳

    Hadron-hadron interactions, as a non-perturbative effect, play a significant role in understanding phenomenological problems in particle physics. Femtoscopy is a powerful tool in heavy-ion collision experiments, enabling the extraction of hadron-hadron interactions via momentum-correlation functions (CFs). These CFs are generally factorized into a convolution of source functions and hadron-hadron wave functions, with the latter encoding information about hadron-hadron interactions. However, source functions remain ambiguous and are commonly approximated by a Gaussian form. Reconstructing source functions from experimental correlation data constitutes an ``inverse problem." To address it, we propose a toy model based on the Tikhonov regularization. Employing a square potential well of four distinct potential strengths, we calculate the CFs for inputs of a Gaussian source function and its hybrid form. The obtained CFs are subsequently used to reconstruct the source functions via the Tikhonov regularization. Our results demonstrate that the Gaussian source function can be successfully reconstructed, indicating the potential of this approach for extracting realistic source functions of hadron pairs of interest in the future.

    hep-phCPC(2026)·6 citations
14. 14*

    Could electron-top interactions spoil the measurement of the Higgs trilinear? -A quantitative estimate at future lepton colliders-

    Lukas Allwicher🇩🇪 · Christophe Grojean🇩🇪 · Lucine Tabatt🇩🇪

    The measurement of the Higgs self-coupling is considered the next milestone in the study of the Higgs boson properties. At future $e^{+}{e}^{-}$ facilities below the double Higgs production threshold, this is extracted from the $Zh$ production cross-section, which is sensitive to the trilinear coupling at the one-loop level. At the same perturbative order, potential effects beyond the Standard Model (SM) may affect the Higgstrahlung rate and distort the self-coupling determination. We study the question focusing especially on contact interactions containing two electron and two top-quark fields. We conclude that, in the context of FCC-ee and its planned runs at different energies, $eett$ interactions change the Higgs self-coupling sensitivity below the percent level. Even in the most pessimistic scenarios, we confirm a robust sensitivity of the order of 17% at the 1$\sigma$ confidence level under the assumption of otherwise SM-like Higgs couplings. A crucial role in these results is played by the measurement of fermion pair production above the $Z$ resonance.

    hep-phJHEP(2026)·3 citations
15. 15*

    Constraining and Resolving Lorentz-Violating New Physics at ESSnuSB Using Complementarity with DUNE

    Himanshu Bora🇮🇳 · Debajyoti Dutta🇮🇳 · Abinash Medhi🇮🇳

    We examine the sensitivity of the ESSnuSB and DUNE long-baseline neutrino experiments to isotropic, CPT-violating Lorentz Invariance Violation (LIV). Using detailed simulations for the 360 km and 540 km ESSnuSB baselines and the 1300 km DUNE setup, we assess how LIV parameters influence oscillation probabilities, event spectra, and degeneracies among oscillation parameters. We find that LIV-induced modifications can closely mimic variations in ${\theta }_{23}$ and ${\delta }_{\mathrm{CP}}$, potentially leading to incorrect determination of the atmospheric mixing angle octant and the leptonic CP phase if LIV effects are not accounted for. Although combining the two ESSnuSB baselines improves overall sensitivity, it does not fully remove these degeneracies. In contrast, a joint ESSnuSB+DUNE analysis benefiting from the synergy between second-maximum sensitivity at ESSnuSB and first-maximum, matter-enhanced sensitivity at DUNE can successfully resolve all these degeneracies and can yield significantly stronger constraints on all the LIV parameters. The results presented here highlights the essential role of multi-baseline, multi-energy experimental strategies to probe Planck-suppressed Lorentz-violating new physics.

    hep-phJHEP(2026)·4 citations
16. 16*

    Massive tree-level splitting functions beyond kinematical limits

    Stefan Höche🇺🇸 · Matt LeBlanc🇺🇸 · Jennifer Roloff🇺🇸 · Grant Whitman🇺🇸

    We present a compact form of the massive $1\to 3$ tree-level QCD splitting functions and discuss a decomposition of the results in terms of lower-order expressions, scalar dipole antenna functions and pure higher-order remainders. The two-gluon radiator functions introduced in this context are novel and generalize expressions obtained from the double-soft approximation. Our results are obtained without reference to soft or quasi-collinear limits.

    hep-phPRD(2026)·3 citations
17. 17*

    Minimal lepton models with non-holomorphic modular $A_4$ symmetry

    Xiang-Yan Gao🇨🇳 · Cai-Chang Li🇨🇳

    We present a comprehensive bottom-up analysis of lepton mass and mixing based on the non-holomorphic $A_4$ modular symmetry. Neutrinos are assumed to be Majorana particles and the light neutrino masses are generated through the Weinberg operator. In this framework, we construct all phenomenologically viable models with minimal number of free parameters, where the Yukawa couplings are expressed in terms of polyharmonic Maaß forms of weights $\pm 4$, $\pm 2$ and $0$ at level $N=3$. Without imposing generalized CP (gCP) symmetry, we identify 147 (6) viable models with seven real free parameters that successfully reproduce the current experimental data of lepton sector for the normal (inverted) mass ordering. When gCP symmetry consistent with $A_4$ modular symmetry is included, the number of free parameters is reduced by one, yielding 47 (5) phenomenologically viable models in the normal (inverted) mass ordering. Finally, we present detailed numerical analyses of a representative model for both mass orderings to illustrate these results.

    hep-phCPC(2026)·10 citations
18. 18*

    Chiral, parity-doublet, effective-Lagrangian mean-field theories for nuclear and astrophysical phenomenology

    Ayon Mukherjee🇮🇳

    Chiral-parity (parity-doublet) effective Lagrangian models provide a compact and symmetry-consistent framework for describing baryons and their negative-parity partners in terms of linearly-realized chiral symmetry. Unlike the conventional, linear, sigma model; the parity-doublet approach accommodates a chirally-invariant mass term, $m_0$, allowing finite baryon-masses even when the chiral condensate melts. This feature enables a unified treatment of hadronic matter across vacuum, nuclear and dense astrophysical regimes. This compact review summarizes the key structures of parity-doublet Lagrangians; outlines the mean-field formulation for nuclear and stellar matter; and highlights recent phenomenological and lattice constraints on the chirally-invariant mass. Emphasis is placed on mirror versus naïve chiral assignments; the role of vector interactions in achieving nuclear saturation; and the implications of parity doubling for the equation-of-state of dense matter and neutron-star cooling. The review concludes with current theoretical challenges and perspectives for extending these models beyond the mean-field approximation.

    hep-phnucl-thInt.J.Mod.Phys.A(2026)·0 citations
19. 19*

    Probing flavor-diagonal couplings of doubly-charged scalar at low and high energies

    Gang Li🇨🇳 · Jin Sun🇰🇷

    We investigate the phenomenology of a TeV-scale doubly-charged scalar from the right-handed sector within the framework of left-right symmetric models. Focusing on its flavor-diagonal couplings to right-handed electrons and muons, we assess probes from both high-energy colliders and low-energy precision experiments. High-energy processes include Bhabha scattering at LEP and future circular electron-positron colliders (CEPC/FCC-ee), direct production at the LHC, and dedicated searches and precision measurements at proposed muon colliders and $\mu$TRISTAN. Low-energy observables encompass parity-violating Møller scattering, muon anomalous magnetic moment, and muonium-antimuonium oscillations. Our combined analysis indicates that for a doubly-charged scalar in the $1$-$3$ TeV range, the flavor-diagonal Yukawa couplings to electrons and muons as small as $10^{-2}$ are accessible. Observations of such a doubly-charged scalar would potentially point toward the type-I seesaw mechanism of neutrino masses in the left-right symmetric model with $D$-parity breaking.

    hep-phPRD(2026)·1 citation
20. 20*

    Black Holes as Catalysts for Cosmic String Detection and Axion Dark Matter Genesis

    Ishan Swamy🇮🇳 · Deobrat Singh🇮🇳

    The global $U_{PQ}(1)$ Peccei-Quinn (PQ) symmetry, proposed to resolve the strong CP problem, predicts the existence of the axion, a pseudo Nambu-Goldstone boson and a leading dark matter candidate. The spontaneous breaking of this symmetry generates global strings that decay predominantly via the emission of massive axions and gravitational waves. In this work, we investigate the decay of cosmic axion strings in the vicinity of a Schwarzschild black hole and estimate the corresponding energy losses and decay timescales of the resulting string loops. For primordial black holes (PBHs) with masses as small as $10^{-16}{M}_{\odot }$, the total radiated energy by the string is found to be on the order of $10^{27}$ GeV, encompassing both axion emission and gravitational waves. A key finding is that the presence of a central black hole significantly accelerates the decay of cosmic string loops, substantially reducing their lifetimes. We present these results as an initial estimate of axion radiation from PBH-cosmic string systems along with the decay time as an important observational signature for axions strings.

    hep-phastro-ph.HEhep-th0 citations
21. 21*

    Dark-pion dark matter beyond leading order: unitarized chiral dynamics

    Yuki Watanabe🇯🇵

    Dark pions are promising dark matter candidates, yet most analyses rely on leading-order (LO) chiral perturbation theory (ChPT). Motivated by the fact that, even for QCD pi-pi scattering, LO ChPT near threshold underestimates the isoscalar s-wave amplitude by an O(1) factor relative to high-precision dispersive results, we quantify how unitarization modifies the standard LO ChPT picture using the chiral unitary method, a nonperturbative resummation that implements the correct analytic structure with minimal input, and assess its impact on the phenomenology of dark-pion dark matter, taking SIMP and WIMP scenarios as canonical examples. We fix the subtraction constant to its natural estimate, interpreted as an effective cutoff at the chiral scale, so that the unitarized amplitudes depend only on the dark-pion mass and decay constant. We show that, depending on the coupling, the unitarized amplitudes develop resonance poles absent at LO, leading to sizable departures in 2-to-2 self-scattering, relevant for SIMP scenarios, and in annihilation including initial-state interaction effects, relevant for WIMP scenarios. These modifications, in turn, affect the viable parameter space. Although the subtraction constant is, from a model-building perspective, merely a parameter, a substantial deviation from its natural value would point to additional elementary resonances with the same quantum numbers.

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

    Timelike showers with jet recoils

    Jack Helliwell🇦🇺 · Ludovic Scyboz🇦🇺 · Peter Skands🇦🇺

    We propose a new way to impose four-momentum conservation on timelike parton-shower branchings, allowing for recoil to be imparted not only to individual partons but also to groups of partons, "jets". In this work we present an explicit realisation of this idea for a dipole parton-shower, using angular ordering to decide which partons are grouped into jets in a way that does not require explicit jet clustering at each stage of the evolution. We verify that the algorithm satisfies next-to-leading logarithmic (NLL) accuracy criteria, from numerical fixed-order tests as well as resummation tests across a range of observables. Our conclusion is that jet recoils provide a viable path for adapting existing dipole/antenna-type showers to achieve NLL accuracy.

    hep-phJHEP(2026)·2 citations
23. 23*

    Practical predictions for the effects of acceleration on decay

    Wim Beenakker🇳🇱 · David Venhoek🇳🇱

    We make predictions of the effects of acceleration on decay rate for three benchmark processes spanning alpha, beta and isomeric decay. These processes are observed to require lower acceleration than that required by previously studied processes. In particular for the case of isomeric decay of Thorium 229m the effects of acceleration are found to be tantalizingly close to being observable with next generation particle accelerators.

    hep-phhep-ex0 citations
24. 24*

    KIGNet: Physics-Motivated Multi-Graph Representation Learning for Explainable Jet Tagging

    Md Raqibul Islam · Adrita Khan🇺🇸 · Mir Sazzat Hossain · Choudhury Ben Yamin Siddiqui · Md. Zakir Hossan · Tanjib Khan🇧🇩 · M. Arshad Momen🇧🇩 · Amin Ahsan Ali🇨🇦 · AKM Mahbubur Rahman

    Jet identification plays a central role in analyzing data from high-energy collider experiments. While deep learning has improved jet classification, it often lacks interpretability. We introduce the Kinematic Interaction Graph Network (KIGNet), a graph neural network that integrates kinematic variables into jet classification by constructing four graph representations per jet, each weighted by a distinct variable: angular separation ($\Delta$), relative transverse momentum ($k_T$), momentum fraction ($z$), and invariant mass squared ($m^2$). Three of these ($\Delta$, $k_T$, $z$) are motivated by the Lund jet plane, grounded in perturbative QCD factorization; the fourth ($m^2$) adds complementary mass-scale sensitivity for heavy-flavor identification. Using Gradient-weighted Class Activation Mapping (Grad-CAM), we determine which variables dominate classification. Angular separation and relative transverse momentum account for about 76% of the total Grad-CAM attribution (40.72% and 35.67%), with momentum fraction and invariant mass contributing the remaining 24%. This hierarchy is consistent with the soft-collinear structure of QCD radiation in the training data, showing that the network learns physically interpretable representations rather than spurious correlations. On the JetClass dataset, KIGNet achieves a macro-accuracy of 95.07%, macro-AUC of 96.61%, and macro-AUPR of 81.52%, relative improvements of 2.45%, 3.40%, and 19.11% over the state-of-the-art baseline. On the Aspen Open Jets dataset of real CMS collision data, KIGNet produces substantially more structured latent representations than the baseline, reducing the Davies-Bouldin Index by 52.15% ($0.8395\to 0.4017$) and increasing the Dunn Index by 42.33% ($0.0189\to 0.0269$), confirming that physics-informed kinematic encoding generalizes beyond idealized simulation to experimental detector conditions.

    hep-phcs.LGhep-ex1 citation
25. 25*

    The $D_{s0}^{\ast }(2317{)}^{+}$ decay to $D_s^{+}{\pi }^0$ and $D_s^{\ast +}\gamma$

    Pei-Sen Su🇨🇳 · Wen-Tao Lyu🇨🇳 · Wei-Hong Liang🇨🇳 · Eulogio Oset🇪🇸

    We study the strong decay of $D_{s0}^{\ast }(2317{)}^{+}$ to $D_s^{+}{\pi }^0$ considering the coupled channels of $D^0{K}^{+},D^{+}{K}^0,D_s^{+}\eta$ and $D_s^{+}{\pi }^0$ within a picture for the interaction based on the local hidden gauge approach. We also address the problem of the radiative decay to $D_s^{\ast +}\gamma$, using the same information obtained from the molecular picture. We obtain a strong width of the $D_{s0}^{\ast }(2317{)}^{+}$ of about $77\mathrm{keV}$ from coupled channels interaction and a radiative decay of about $1.7\mathrm{keV}$. We also show that the extra consideration of ${\pi }^0-\eta$ mixing can double the strong decay width to values around $140\mathrm{keV}$. The anomalous terms for the radiative decay are considered for the first time, but they are found negligible. We make a thorough discussion of this and other results to the light of the recent measurement of Belle for the ratio of these two decay modes, and make a call for the precise measurement of the two decay widths independently to clarify the present situation concerning the nature of the $D_{s0}^{\ast }(2317{)}^{+}$ state.

    hep-phEPJC(2026)·8 citations
26. 26*

    Precision Higgs Boson Probe of Type-II Seesaw Models

    Saiyad Ashanujjaman🇩🇪 · P. S. Bhupal Dev🇺🇸 · Jihong Huang🇨🇳 · Shun Zhou🇨🇳

    Despite direct searches at the LHC excluding tripletlike Higgs bosons up to several hundred GeV over much of the type-II seesaw model parameter space, parts of it -- most notably those featuring ``cascade decays'' of the charged Higgs bosons into their neutral partners and off-shell $W$ bosons -- still remain unconstrained. Meanwhile, measurements of the diphoton signal strength of the Standard Model (SM) Higgs boson -- potentially modified by loop contributions from tripletlike Higgs states -- are in good agreement with the SM expectation, with combined experimental uncertainties currently at approximately 8%. Given the trend in previous measurements, it is expected that future precision Higgs measurements at the HL-LHC and a future lepton collider such as the Circular Electron Positron Collider, Future Circular Collider, or Muon Collider will be consistent the standard diphoton signal strength, albeit with significantly reduced uncertainties, down to about 0.7%. Presuming this and considering all relevant constraints, we explore whether such increasingly precise diphoton measurements can indirectly probe the parameter space that currently evades direct searches. We find that subpercent-level determinations of the diphoton rate will decisively probe a substantial fraction of this otherwise elusive region.

    hep-phhep-exPRD(2026)·8 citations
27. 27*

    Limits on the diffractive mass in strong coherent ${\gamma }^{\ast }$-nucleus scattering

    A. H. Mueller🇺🇸

    An evolution equation for diffractive production with a definite rapidity gap is given. Coherent ${\gamma }^{\ast }A$ collisions in the unitarity (saturation) region are studied with the conclusion that the diffractive mass is always on the order of the ${\gamma }^{\ast }$ virtuality, $Q$, when the scattering is strong. Deep in the saturation region diffractive masses significantly greater than $Q$ are strongly suppressed by a Levin-Tuchin mechanism.

    hep-phPLB(2026)·2 citations
28. 28*

    Chiral transition in a Non-Abelian Quasi-Particle Model with three quark flavours

    Eleftherios P. Politis🇬🇷 · Antonis Tsapalis🇬🇷 · Fotios K. Diakonos🇬🇷

    We combine the recently introduced Non-Abelian Quasi-Particle Model (NAQPM) for gluons with an ideal Fermi gas of three quark species with the aim to describe the equation of state (energy density vs. temperature) of $2+1$ - flavour Lattice-QCD at zero chemical potential. Allowing temperature dependent masses for the fermions, we show that above a critical temperature $T_c$ the quark mass has to drop rapidly in order to obtain energy density values compatible with the Lattice-QCD results. Within this framework, thus, the restoration of chiral symmetry in the system is observed. Furthermore, we demonstrate that the gluon variance -- which is a fundamental quantity of the NAQPM -- is strongly correlated to the fermion mass and decreases by orders of magnitude through the transition. The high temperature phenomenological characteristics of the gluon appear consistent to properties of the perturbative QCD gluon. The model indicates that color deconfinement and chiral symmetry restoration are interrelated and classical configurations of the QCD dynamics play an important role to the criticality of the system.

    hep-phhep-latnucl-thPLB(2026)·0 citations
29. 29*

    Systematic analysis of 3HDM symmetries

    A. Kunčinas🇵🇹 · P. Osland🇳🇴 · M. N. Rebelo🇵🇹

    Symmetries play a crucial role in shaping the structure and predictions of multi-Higgs-doublet models. In three-Higgs-doublet models considerable effort has been put into classifying possible symmetry groups and the conditions for their realisation, yet the completeness of existing classifications remains an open question. In this work, we revisit the problem of identifying realisable symmetries by re-examining conventional Higgs family and general CP transformations from an alternative perspective. Our analysis identifies certain limitations in previous approaches and introduces a clearer, more systematic framework for model builders. We expand our classification by investigating more generalised symmetry structures - the recently identified GOOFy transformations, which act non-trivially on the Higgs doublets and their conjugates. Our analysis consolidates known results, uncovers previously overlooked structures, and expands the set of symmetries in three-Higgs-doublet models, offering both a clearer theoretical foundation and a practical reference for symmetry-based model building.

    hep-phhep-thPRD(2026)·8 citations
30. 30*

    Prospects for measuring electroweak production of $Z\gamma \gamma$ and 2 jets at the LHC

    Ran Ding🇨🇳 · Ruobing Jiang🇨🇳 · Tianyi Yang🇨🇳 · Andrew Levin🇨🇳 · Qiang Li🇨🇳

    Vector boson scattering (VBS) serves as a powerful channel for probing the Standard Model, particularly the electroweak symmetry breaking mechanism. Currently, studies of VBS mainly focus on $2\to 2$ scattering. In this study, we investigate the $2\to 3$ VBS process of $\text{p p}\to Z\gamma \gamma +2\text{jets}$ through Monte Carlo simulations, including signal generation and background analysis. The signal significance is evaluated across different phase-space regions. With an integrated luminosity of 500 fb${}^{-1}$, the signal significance can reach about 4.5 $\sigma$. These results suggest that, given the ongoing release of the LHC Run 3 dataset, there will be promising opportunities to explore and potentially discover a series of $2\to 3$ VBS processes, starting with the $Z\gamma \gamma$ channel.

    hep-phPRD(2026)·0 citations
31. 31*

    Enhanced active-sterile neutrino polarizability at the intensity frontier

    Julia Gehrlein🇺🇸 · Anil Thapa🇺🇸 · Adrian Thompson🇺🇸

    Electromagnetic probes of neutrinos can provide insights into physics beyond the Standard Model. Among the possible electromagnetic interactions of neutrinos is neutrino polarizability, a dimension-7 effective operator that couples two neutrinos to two photons. In this manuscript, we study a realization of the neutrino polarizability operator in which one of the active neutrinos is replaced by a sterile neutrino. We derive new constraints on this active-sterile neutrino polarizability from its contribution to neutrino-nucleus scattering with a single photon in the final state at neutrino experiments. We show that a realization of this operator via a light mediator can explain the MiniBooNE low-energy excess while remaining consistent with other experimental constraints. Finally, we comment on additional model realizations of this higher-dimensional operator.

    hep-phhep-exPRD(2026)·1 citation
32. 32*

    Sunset integrals with up to three mass scales in chiral perturbation theory: a comparative study of the Mellin-Barnes representation technique

    Balasubramanian Ananthanarayan🇮🇳 · Sumit Banik🇨🇭 · Véronique Bernard🇫🇷 · Samuel Friot🇫🇷 · Shayan Ghosh · Ulf-G. Meißner🇩🇪

    Sunset integrals are among the simplest of two-loop integrals that appear in perturbative quantum field theories and possess up to four distinct mass scales. By means of integration by parts identities, they can be written in terms of four distinct master integrals. In this article, we discuss the independent configurations of on-shell and off-shell sunset master integrals with one, two and three mass scales that arise in chiral perturbation theory. We derive Mellin-Barnes integral representations of these integrals and analytically solve them using various methods to obtain exact results in the form of single and double convergent series of the hypergeometric type, for the values of the mass parameters that allow us to do so. We then discuss how to analytically continue the results to other regions of the parameters and conclude by discussing a few applications in chiral perturbation theory.

    hep-phhep-thEur.Phys.J.ST(2026)·1 citation
33. 33*

    Infrared Freeze-In of Magnetic Dipole Dark Matter

    Asher Berlin🇺🇸 · Jae Hyeok Chang🇺🇸 · Tanner Trickle🇺🇸

    We propose a novel mechanism for the cosmological production of keV - GeV mass dark matter that interacts with the Standard Model through a small effective magnetic dipole moment. Such an interaction can be radiatively generated if dark matter couples to heavier charged particles. Previous studies have focused on the case where these charged states are much heavier than the reheat temperature, such that freeze-in production of dark matter is sensitive to the ultraviolet details of reheating. Here, we instead consider the possibility that these heavy states have masses comparable to the dark matter mass and are charged under a new kinetically-mixed $U(1{)}^{\prime }$. As a result, dark matter production is dominated by the infrared freeze-in of the heavy charged states that subsequently thermalize the rest of the dark sector to a temperature much below that of the visible bath. We delineate regions of parameter space consistent with cosmological and astrophysical constraints and identify benchmark scenarios that can guide the next generation of direct detection experiments searching for spin-dependent scattering of sub-GeV dark matter.

    hep-phastro-ph.COJHEP(2026)·0 citations
34. 34*

    Neutrino Effects on Atomic Measurements of the Weinberg Angle

    Mitrajyoti Ghosh🇺🇸 · Yuval Grossman🇺🇸 · Chinhsan Sieng🇺🇸 · Bingrong Yu🇺🇸

    We derive a complete expression for the neutrino-mediated quantum force beyond the four-Fermi approximation within the Standard Model. Using this new result, we study the effect of atomic parity violation caused by neutrinos. We find that the neutrino effect is sizable compared to the current experimental sensitivity and can also significantly affect the value of the Weinberg angle measured in atomic systems. This offers a promising method for detecting the neutrino force in the future and facilitates the application of precision atomic physics as a probe for neutrino physics and the electroweak sector of the Standard Model.

    hep-phhep-exphysics.atom-phPRL(2025)·3 citations
35. 35*

    Measuring CP violation using quantum state tomography

    M. Fabbrichesi🇮🇹 · R. Floreanini🇮🇹 · E. Gabrielli🇮🇹 · L. Marzola🇪🇪

    We investigate direct CP violation in neutral meson decays by reconstructing the associated density matrices and measuring their difference using the trace distance. Our results cover neutral kaon decays into two scalar triplets of isospin space, specifically the pions, and decays of $B$- and $D$- mesons into two scalar octets of SU(3) flavor space. We briefly discuss the quantum properties of these states, including entanglement, contextuality, and nonlocality. Additionally, we demonstrate a comparable approach for spin-1 final states by employing a density matrix describing states in the space of helicities. The significance of CP violation obtained through this method is consistently comparable, and often surpasses that obtained using only single, or combinations of, asymmetries.

    hep-phhep-exJHEP(2026)·3 citations
36. 36*

    Complete next-to-next-to-leading order QCD corrections to the decay matrix in $\mathbf{B}$-meson mixing at leading power

    Ulrich Nierste🇩🇪 · Pascal Reeck🇩🇪 · Vladyslav Shtabovenko🇩🇪 · Matthias Steinhauser🇩🇪

    We compute next-to-next-to-leading order corrections to the decay width difference of mass eigenstates and the charge-parity (CP) asymmetry $a_{\mathrm{fs}}$ in flavour-specific decays of neutral $B$ mesons. We include both current-current and penguin operators at three-loop order. All input integrals in the transition amplitude are reduced to a small set of master integrals which depend on the ratio of the charm and bottom quark masses. The latter are computed using semi-analytic methods which provide deep expansions around properly selected values of $m_c/m_b$. We provide numerical results for $\Delta \Gamma$ and $\Delta \Gamma /\Delta M$, both for the $B_d$ and $B_s$ system, including a detailed uncertainty analysis. Using the experimental value for the mass difference $\Delta M_s$ we predict $\Delta {\Gamma }_s=(0.078\pm 0.015)\text{mbox}{ps}^{-1}$. For the CP asymmetries we find $a_{\mathrm{fs}}^s=(2.27\pm 0.13)\times 10^{-5}$ and $a_{\mathrm{fs}}^d=-(5.19\pm 0.30)\times 10^{-4}$. Furthermore, we show that the ratios $(\Delta {\Gamma }_s/\Delta M_s)/(\Delta {\Gamma }_d/\Delta M_d)$ and $\Delta {\Gamma }_d/\Delta {\Gamma }_s$ can be predicted with high precision. The former quantity permits the prediction $\Delta {\Gamma }_d=(0.00215\pm 0.00013)\text{mbox}{ps}^{-1}$ from the measurements of $\Delta M_{d,s}$ and $\Delta {\Gamma }_s$. We further discuss the impact of $\Delta {\Gamma }_d/\Delta {\Gamma }_s$ on the CKM unitarity triangle and present ready-to-use formulae which permit improved predictions once updated results for the operator matrix elements are available.

    hep-phhep-exJHEP(2026)·3 citations
37. 37*

    Theory of inverse beta decay for reactor antineutrinos

    Oleksandr Tomalak🇨🇳 · Qishan Liu🇨🇳 · Yu-Feng Li🇨🇳

    Inverse beta decay (IBD), ${\overline{\nu }}_{e}p\to e^{+}n\left(\gamma \right)$, is the main detection channel for reactor antineutrinos in water- and hydrocarbon-based detectors. As reactor antineutrino experiments now target sub-percent-level sensitivity to oscillation parameters, a precise theoretical description of IBD, including recoil, weak magnetism, nucleon structure, and radiative corrections, becomes essential. In this work, we give a detailed and precise calculation of the total and differential cross sections for radiative IBD, ${\overline{\nu }}_{e}p\to e^{+}n\gamma$. We use a heavy baryon chiral perturbation theory framework, systematically incorporating electroweak, electromagnetic, and strong-interaction corrections. We derive new analytic cross-section expressions, clarify the collinear structure of radiative corrections, and provide a systematic uncertainty analysis. We also discuss phenomenological applications for reactor antineutrino experiments, e.g., JUNO, and neutron decay. Our results enable sub-permille theoretical precision, supporting current and future experiments.

    hep-phhep-exnucl-exnucl-thPhys. Rev. D (2026)·8 citations
38. 38*

    Radiative corrections to inverse beta decay: a precision analysis for reactor neutrinos

    Oleksandr Tomalak🇨🇳

    We present a complete calculation of radiative corrections to the inverse beta decay reaction, ${\overline{\nu }}_e+p\to e^{+}+n$, at reactor antineutrino energies using heavy-baryon chiral perturbation theory. Our analysis consistently incorporates quantum electrodynamics, chromodynamics, and electroweak contributions for the first time within this framework. We provide updated, high-precision cross-section predictions with a full error budget and present the positron energy spectrum, including radiative effects. The results are essential for normalizing the reactor antineutrino flux, determining neutrino oscillation parameters with subpercent accuracy, and searching for new physics at nuclear power plants.

    hep-phhep-exnucl-exnucl-thPhys. Rev. Lett. (2026)·5 citations
39. 39*

    Generalized tension metrics for multiple cosmological datasets

    Matías Leizerovich🇦🇷 · Susana J. Landau🇦🇷 · Claudia G. Scóccola🇨🇱

    We introduce a novel estimator to quantify statistical tensions among multiple cosmological datasets simultaneously. This estimator generalizes the Difference-in-Means statistic, $Q_{\mathrm{DM}}$, to the multi-dataset regime. Our framework enables the detection of dominant tension directions in the shared parameter space. It further provides a geometric interpretation of the tension for the two- and three-dataset cases in two dimensions. According to this approach, the previously reported increase in tension between DESI and Planck from $1.9\sigma$ (DR1) to $2.3\sigma$(DR2) is reinterpreted as a more modest shift from $1.18{\sigma }^{\mathrm{eff}}$ (DR1) to $1.45{\sigma }^{\mathrm{eff}}$ (DR2). These new tools may also prove valuable across research fields where dataset discrepancies arise.

    ↳ astro-ph.COastro-ph.IMhep-exhep-ph+10 citations
40. 40*

    Pion and Kaon PDFs from Lattice QCD via Large Momentum Effective Theory and Short-Distance Factorization

    Joshua Miller🇺🇸 · Joseph Torsiello🇺🇸 · Isaac Anderson🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Joseph Delmar🇺🇸 · Sarah Lampreich🇺🇸

    In this work, we present a first-principles lattice-QCD calculation of the unpolarized quark PDF for the pion and the kaon. The lattice data rely on matrix elements calculated for boosted mesons coupled to non-local operators containing a Wilson line. The calculations on this lattice ensemble correspond to two degenerate light, a strange, and a charm quark ($N_f=2+1+1$), using maximally twisted mass fermions with a clover term. The lattice volume is $32^3\times 64$, with a lattice spacing of 0.0934 fm, and a pion mass of 260 MeV. Matrix elements are calculated for hadron boosts of $|P_3|=0,0.41,0.83,1.25,1.66,$ and 2.07 GeV. To match lattice QCD results to their light-cone counterparts, we employ two complementary frameworks: the large-momentum effective theory (LaMET) and the short-distance factorization (SDF). Using these approaches in parallel, we also test the lattice data to identify methodology-driven systematics. Results are presented for the standard quark PDFs, as well as the valence sector. Beyond obtaining the PDFs, we also explore the possibility of extracting information on SU(3) flavor-symmetry-breaking effects. For LaMET, we also parametrize the momentum dependence to obtain the infinite-momentum PDFs.

    ↳ hep-lathep-exhep-phhep-thPRD(2026)·8 citations
41. 41*

    Maximally Symmetric Boost-Invariant Solutions of the Boltzmann Equation in Foliated Geometries

    Mauricio Martinez🇺🇸 · Christopher Plumberg🇺🇸

    In this work we study the relativistic kinetic theory of a boost-invariant conformal gas on a static, maximally symmetric background $d{S}_3\times \mathbb{R}$, considering all constant-curvature slicings of $d{S}_3$ - flat, spherical, or hyperbolic- and their associated symmetry groups. Using a symmetry-driven cotangent-bundle approach, we show that the isometry group of each slicing acts on phase space in such a way that only its Casimir invariants and the time-like coordinate unconstrained, so the distribution function depends solely on these quantities. This yields a unified boost-invariant exact solution of the Boltzmann equation valid for each constant-curvature foliation of $d{S}_3\times \mathbb{R}$. Specializing this general solution to the flat and spherical foliations reproduces the Bjorken and Gubser flows, respectively, while its restriction to the hyperbolic foliation produces a genuinely new analytic solution (`Grozdanov flow'). Hydrodynamics and free streaming emerge naturally as limiting regimes of this novel exact solution. We further comment on several relevant aspects of the new boost-invariant solution on the hyperbolic slicing and on their interpretation once mapped back to Minkowski space.

    ↳ hep-thcond-mat.stat-mechgr-qchep-ph+1PRD(2026)·2 citations
42. 42*

    Testing the weak equivalence principle for nonclassical matter with torsion balances

    Roberto Onofrio🇺🇸 · Alexander R. H. Smith🇺🇸 · Lorenza Viola🇺🇸

    We propose tests of the weak equivalence principle (WEP) using a torsion balance, in which superposition of energy eigenstates are created in a controllable way for the test masses. After general considerations on the significance of tests of the WEP using quantum states and the need for considering inertial and gravitational masses as operators, we develop a model to derive the matrix elements of the free-fall operator, showing that the variance of the acceleration operator, in addition to its mean, enables estimation of violations of the WEP due to quantum coherence in a way that is robust with respect to shot-to-shot fluctuations. Building on this analysis, we demonstrate how the validity of the WEP may be tested in a torsion balance setup, by accessing the mean and variance of a torque operator we introduce and quantize. Due to the long acquisition times of the signal as compared to the timescale on which coherent superposition states may survive, we further propose a dynamical setting, where the torsion balance is subject to a time-dependent gravitational field, and measurements of angular acceleration encode possible violations of the WEP.

    ↳ quant-phgr-qchep-phPRD(2025)·1 citation
43. 43*

    Identified charged hadron production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 54.4 GeV with the STAR detector

    STAR Collaboration: B. E. Aboona🇺🇸 · J. Adam🇨🇿 · G. Agakishiev🇷🇺 · I. Aggarwal🇮🇳 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · A. Aitbayev🇷🇺 · I. Alekseev🇷🇺 · E. Alpatov🇷🇺 · A. K. Alshammri🇺🇸 · A. Aparin🇷🇺 · S. Aslam🇮🇳 and 375 other authors

    We present results on the production of ${\pi }^{\pm }$, $K^{\pm }$, $p$, and $\bar{p}$ in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 54.4~GeV using the STAR detector at RHIC, at midrapidity ($|y|<$ 0.1). Invariant yields of these particles as a function of transverse momentum are shown. We determine bulk properties such as integrated particle yields ($dN/dy$), mean transverse momentum ($⟨p_T⟩$), particle ratios, which provide insight into the particle production mechanisms. Additionally, the kinetic freezeout parameters ($T_{\text{kin}}$ and $⟨{\beta }_T⟩$), which provide information about the dynamics of the system at the time of freezeout, are obtained. The Bjorken energy density (${ϵ}_{\mathrm{BJ}}$), which gives an estimate of the energy density in the central rapidity region of the collision zone at the formation time $\tau$, is calculated and presented as a function of multiplicity for various energies. The results are compared with those from the models such as A Multi-Phase Transport (AMPT) and Heavy Ion Jet INteraction Generator (HIJING) for further insights.

    ↳ nucl-exhep-exhep-phhep-th+1PRC(2026)·2 citations
44. 44*

    Quantum Corrections to Randall-Sundrum Model from JT Gravity

    Ying-Jian Chen🇨🇳 · Jun Nian🇨🇳

    We investigate quantum corrections to the Randall-Sundrum (RS) model in the near-extremal black brane background with quantum corrections in the near-horizon. The near-horizon geometry is described by Jackiw-Teitelboim gravity, and the quantum fluctuations are governed by the Schwarzian action. We introduce the Schwarzian modes into the RS metric, derive the quantum-corrected equation for the Kaluza-Klein (KK) modes via the Schwinger-Dyson equation, calculate the correction to the KK mass spectrum, and discuss the impact of quantum corrections on the Goldberger-Wise mechanism. Our work introduces both quantum corrections and temperature into the RS model, providing insights into cosmology and phase transitions within it.

    ↳ hep-thgr-qchep-phPRD(2026)·3 citations
45. 45*

    Probing memory-burdened Primordial Black Holes with global 21 cm signal

    Priyanka Sarmah🇹🇼 · Kingman Cheung🇹🇼

    We investigate the imprints of memory-burdened primordial black holes (PBH) on the global 21 cm signal during the cosmic dawn. Recent studies reopened the possibility of a mass window of PBHs as a compelling candidate for dark matter, particularly in low-mass regimes ($M_{\text{PBH}}<10^{15}$ g) where conventional constraints from evaporation are being revisited in light of quantum gravitational effects. One such effect, the \textit{memory burden effect}, slows down black hole evaporation by incorporating the backreaction of radiation on the black hole microstates, substantially extending the lifetime of light PBHs and thus modifying their late-time emission spectra. This prolonged emission can dramatically alter the energy injection history in the early universe. By computing the modified energy injection rates into the intergalactic medium and incorporating them into the thermal and ionization evolution of neutral hydrogen, we obtain projected constraints on the fraction of dark matter. The bounds are obtained from the fact that these low mass PBHs, which were thought otherwise evaporated, can modify the absorption amplitude in the global 21 cm signal at redshift $z\approx 17$. Considering the two viable scenarios of transition to the memory-burden phase: fast (or instantaneous) and slow (transition with a finite width), we show how the 21 cm bounds are sensitive to different mass ranges. For a broad transition with $\delta =10^{-2}$ we find that PBHs in the mass range $M_{\mathrm{PBH}}\simeq 10^8$-$10^{13}$ g are excluded at the level of $f_{\mathrm{PBH}}\gtrsim 10^{-8}$. In contrast, for a fast-transition case ($k=1$), the evaporation is suppressed so efficiently that no meaningful 21 cm constraint remains for $M_{\mathrm{PBH}}\gtrsim 10^7$ g.

    ↳ astro-ph.COhep-ph3 citations
46. 46*

    Over-abundant gamma-like signals around Solar disk shadows by twin bent and smeared muon and electron pairs secondaries, versus rare local TeV gamma

    Daniele Fargion🇮🇹 · Omar Tibolla🇲🇽 · Pier Giorgio De Sanctis Lucentini🇷🇺 · Sara Turriziani · Sarah Kaufmann🇲🇽 · Danila Sopin🇷🇺 · Maxim Yu. Khlopov🇫🇷

    Cosmic rays with energies of tens of TeV and above, skimming the Sun, could fragment into pions. The resulting gamma photons and muons, as well as subsequent electron pairs, will reach us in the form of gamma or electromagnetic air-showers , gamma-like air-showers on Earth. Their multiple presence may soon be observed and disentangled by the LHAASO telescope array.

    ↳ astro-ph.HEastro-ph.SRhep-phPoS(2025)·2 citations
47. 47*

    SS433 PeV neutron jet feeding the far TeV gamma beam

    Daniele Fargion🇮🇹 · Pier Giorgio De Sanctis Lucentini🇷🇺 · Sara Turriziani · Danila Sopin · Maxim Yu. Khlopov🇫🇷

    The SS433 is a well-known binary system with an internal black hole, which is stripping mass from an orbiting companion of ten solar masses, at a hundred of light-seconds away. The black hole and its accretion disk fuel a thin precessing jet, whose spirals are well-observed. Surprisingly, disconnected gamma-ray tails have recently been discovered by H.E.S.S., HAWC and LHAASO, hundreds of light-years away and with energies of tens of TeV. We suggest that tens PeV neutron burst jets were ejected from the SS433 system over the past century. These beams of ultra high-energy PeVatron neutrons, by their in-flight beta decay and Inverse Compton scattering, could be the source of the enigmatic, distant and disconnected tens of TeV gamma-ray beams. These ultra-relativistic PeV neutron jets could have been formed during one of the system's rare and intense tidal eruptions, when tens of PeV protons collide CV October 2025 with thermal ultraviolet photons, creating delta resonances. Their decay into secondary neutron beams of tens of PeV is well consistent with observations. Alternative models appear uncompetitive.

    ↳ astro-ph.HEastro-ph.GAastro-ph.IMhep-phPoS(2025)·0 citations
48. 48*

    Paucity of downward UHE neutrino tracks in IceCube versus unexpected huge KM3-230213A event: solving the puzzles?

    D. Fargion🇮🇹

    Recently the ARCA array detector published the down-ward-horizontal event: the KM3-230213A. It appeared as the most energetic neutrino ever observed: about 200 PeV (2 10^17 eV) up to EeV (10^18 eV) energy. This huge value, is puzzling. It is not statistically consistent with several upper bound derived by two greater and longer life detectors: by IceCube and in particular by AUGER array. Asymmetry in recent IceCube neutrino alert tracks upward and downward at same horizontal angles as ARCA one, suggest that they are mostly polluted atmospheric muon bundles. This paucity also disfavor the skimming neutrino interpretation by ARCA. We suggest that the array floating and bending in the deep sea may lead, sometime, to a misleading geometry that is pointing to a wrong arrival angle direction: a much less horizontal muon (neutrino) track respect to a much real one, more inclined and vertical, due to atmospheric muon bundle or charmed single event. Contrary to present argument, if such a rare event would be soon rediscovered in data or re-observed, it would open the road to a new guaranteed Tau neutrino Astronomy. At EeV energy such upward tau air-showers should shine AUGER telescopes or blaze future satellite in Space. A previous model in astrophysics considered energetic neutrino E>>100 EeV, neutrino scattering, onto cosmic, relic, light mass ones. Their ultra-relativistic Z boson resonance formation and its decay in flight would produce hadron UHECR relics around tens-hundred EeV energy. Explaining how sources located at far distances, above the usual GZK hundred Mpc, cut off ones, may shine and cluster in AUGER or TA data.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-ex+1PoS(2025)·1 citation
49. 49*

    Machine Learning-based Unfolding for Cross Section Measurements in the Presence of Nuisance Parameters

    Huanbiao Zhu🇺🇸 · Krish Desai🇺🇸 · Mikael Kuusela🇺🇸 · Vinicius Mikuni🇯🇵 · Benjamin Nachman🇺🇸 · Larry Wasserman🇺🇸

    Statistically correcting measured cross sections for detector effects is an important step across many applications. In particle physics, this inverse problem is known as unfolding. In cases with complex instruments, the distortions they introduce are often known only implicitly through simulations of the detector. Modern machine learning has enabled efficient simulation-based approaches for unfolding high-dimensional data. Among these, one of the first methods successfully deployed on experimental data is the OmniFold algorithm, a classifier-based Expectation-Maximization procedure. In practice, however, the forward model is only approximately specified, and the corresponding uncertainty is encoded through nuisance parameters. Building on the well-studied OmniFold algorithm, we show how to extend machine learning-based unfolding to incorporate nuisance parameters. Our new algorithm, called Profile OmniFold, is demonstrated using a Gaussian example as well as a particle physics case study using simulated data from the CMS Experiment at the Large Hadron Collider.

    ↳ stat.APhep-exhep-phphysics.data-an+12 citations
50. 50*

    Universal relation involving fundamental modes in two-fluid dark matter admixed neutron stars

    Hajime Sotani🇯🇵 · Ankit Kumar🇯🇵

    We systematically investigate the fundamental oscillation frequencies of dark matter admixed neutron stars, focusing on models with self-interacting fermionic dark matter that couples to normal matter solely through gravity. The analysis is carried out within a two-fluid formalism under the relativistic Cowling approximation, where the perturbation equations follow from the linearized energy-momentum conservation laws of both components. We find that the mass-scaled fundamental frequencies of the nuclear (dark) fluid in dark core (halo) configurations exhibit a remarkably tight correlation with the total stellar compactness. This universality persists across the dark matter parameter space explored in this study and is largely insensitive to the choice of nuclear equation of state. In contrast, we also find the breakdown of such universality with the tidal deformability, i.e, the same frequencies show substantial deviations from universality when expressed in terms of the tidal deformability. These contrasting behaviors highlight possible observational imprints of dark matter in neutron star interiors.

    ↳ astro-ph.HEhep-phEPJC(2025)·12 citations
51. 51*

    Bayesian Inference of Heavy-Quark Dissipation and Jet Transport Parameters from D-Meson observables in heavy-ion collisions at the LHC energies

    Xu-Fei Xue🇨🇳 · Zi-Xuan Xu🇨🇳 · Wei Dai🇨🇳 · Jiaxing Zhao🇩🇪 · Ben-Wei Zhang🇨🇳

    We perform the first simultaneous Bayesian inference of the temperature-dependent heavy-quark spatial diffusion coefficient $2\pi T{\mathcal{D}}_s$ and the scaled jet transport coefficient $\hat{q}/T^3$ in the quark-gluon plasma, utilizing $D$-meson nuclear modification factor $R_{\text{AA}}$ and elliptic flow $v_2$ data from Pb-Pb collisions at $\sqrt{s_{\text{NN}}}=5.02\text{TeV}$. The analysis employs a unified improved Langevin transport model that incorporates both collisional and radiative energy loss, followed by coalescence plus fragmentation hadronization. The posterior distributions of the parameters of $\hat{q}/T^3$ and those of $2\pi T{\mathcal{D}}_s$ are well constrained, and compared with the results of theoretical models or other experimental data extraction, respectively. The $30-50\%$ centrality data provide significantly stronger constraints than the $0-10\%$ data. The extracted ratio $\hat{q}/\kappa$ between the quark jet transport and heavy-quark diffusion coefficients exhibits a non-monotonic temperature dependence, deviating from the value $2$ estimated from the definition, with a value interval spanning 0.25--0.8 corresponding to the mean values of the inferred parameters. This work establishes a data-driven quantitative relationship between these two fundamental transport properties in the same observables, offering crucial insight into their interplay in the strongly coupled medium.

    ↳ nucl-thhep-phPRC(2026)·3 citations
52. 52*

    Modified vacuum polarization in the presence of a plasma

    Sebastian Lundström🇸🇪 · Philip Semrén🇸🇪 · Haidar Al-Naseri🇺🇸 · Gert Brodin🇸🇪

    We study vacuum polarization due to strong fields, in the presence of an electron-positron plasma. For this purpose, we expand quantum kinetic equations using weak fields and slow temporal scales as expansion parameters. It is demonstrated that the evolution of the Dirac field can be described by classical-like distribution functions for electrons and positrons, which are weakly coupled through quantum interactions. Furthermore, we deduce that these coupling terms give rise to well-known expressions for vacuum polarization, in addition to quantum modifications proportional to the content of real particles. Depending on the initial plasma density, the dominant quantum corrections to classical evolution may arise from real particle couplings or from the vacuum polarization associated with virtual particles. The implications of our results are discussed.

    ↳ physics.plasm-phhep-phhep-thPhys.Plasmas(2026)·0 citations
53. 53*

    Bound and Resonant States of Muonic Few-Body Coulomb Systems: Extended Stochastic Variational Approach

    Liang-Zhen Wen🇨🇳 · Shi-Lin Zhu🇨🇳

    We compute the bound and resonant states of hydrogen-like muonic ions ($\mu \mu p$, $\mu \mu d$, $\mu \mu t$) and three-body muonic molecular ions ($pp\mu$, $pd\mu$, $pt\mu$, $dd\mu$, $dt\mu$, $tt\mu$), and the four-body double-muonic hydrogen molecule ($\mu \mu pp$) using an extended stochastic variational method combined with complex scaling. The approach provides a unified treatment of bound and quasibound states and achieves an energy accuracy better than $0.1\mathrm{eV}$ across all systems studied. Complete spectra below the corresponding $n=2$ atomic thresholds are obtained, including several previously unresolved shallow resonances in both three- and four-body sectors.

    ↳ physics.atom-phhep-exhep-phnucl-exPRA(2026)·3 citations
54. 54*

    The Knizhnik--Zamolodchikov structure of lattice BFKL evolution and the twist-two anomalous dimension

    Josep Rubí Bort (1)🇪🇸 · Agustín Sabio Vera (1 and 2)🇪🇸 · Eduardo Serna Campillo (2) ((1) Instituto de Física Teórica UAM-CSIC, Nicolás Cabrera 15, E-28049 Madrid, Spain, (2) Theoretical Physics Department, Universidad Autónoma de Madrid, E-28049 Madrid, Spain)🇪🇸

    We study a lattice regularization of the BFKL evolution, showing its bulk dynamics is governed by an abelian Knizhnik--Zamolodchikov equation. The Hamiltonian combines long-range hopping with virtual corrections encoded by harmonic numbers. An exact walk expansion renders Reggeisation manifest at finite system size. In the bulk continuum limit, evolution reduces to a connection on ${\mathbb{P}}^1\setminus \{0,1,\infty \}$: $\Omega (x)=-2dx/x-4dx/(1-x)$, with solutions in $\{0,1\}$-alphabet harmonic polylogarithms. Projecting to the collinear sector via Brown's single-valued map organizes the twist-two anomalous dimension's small-$\omega$ expansion, generating polynomials in odd zeta values, matching the transcendentality structure of planar $\mathcal{N}=4$ SYM and multi-Regge kinematics. The lattice thus isolates the algebraic core of BFKL evolution.

    ↳ hep-thhep-ph0 citations
55. 55*

    Open Effective Field Theory and the Physics of Cosmological Collider Signals

    Thomas Colas🇬🇧 · Zhehan Qin🇨🇳 · Xi Tong🇬🇧

    We examine the origin of the cosmological collider signal using the framework of open effective field theories. Focusing on the single exchange of a massive scalar field, we demonstrate that the trispectrum splits cleanly into its local and non-local components once the heavy-field propagators are decomposed in the Keldysh basis. Integrating out the massive degree of freedom yields a single-field effective field theory for the light scalar that necessarily contains both unitary operators and non-unitary contributions associated with dissipation and stochastic noise. We show that the leading local signal in parity-preserving theories arises from the unitary part of this effective field theory, whereas the non-local signal is intrinsically associated with its stochastic sector. The effective field theory coefficients themselves are a priori non-analytic in the external kinematics; however, this non-analyticity can be softened when a scale hierarchy - such as the heavy-mass expansion - is imposed, up to spurious contributions that ultimately cancel in observables. Finally, we establish a connection between the cosmological collider signal and entropy production, linking the observable non-local signal to intrinsic properties of the quantum state, including its degree of mixedness.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2026)·16 citations
56. 56*

    Strong-field regime within effective field theory

    Sebastián Franchino-Viñas🇦🇷 · Jérémie Quevillon🇫🇷 · Diego Saviot🇫🇷

    Building upon the Covariant Derivative Expansion, we develop a method to compute effective actions that is able to capture non-perturbative effects induced by strong background fields. We demonstrate the method in scalar QED, by deriving the full second-derivative corrections to the scalar Heisenberg--Euler effective action. The corresponding result is interpreted as an effective field theory with three characteristic scales, two of which are large (mass and field strength) in comparison with the remaining one (derivatives of the field). As an application, we show that, at this order, the transseries structure of the Schwinger pair production rate is preserved, even if the involved coefficients are modified. Our analysis also helps clarify recent disagreements concerning the coefficients of this effective action.

    ↳ hep-thhep-phquant-ph2 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.