Wed·Oct 29, 2025Wednesday·October 29, 2025

1. 01*

   String Decomposition and Gravitational Waves in High-quality Axion Gauge Theories

   Camilla Mupo🇨🇦 · Yue Zhang🇨🇦

   The QCD axion can successfully solve the strong CP problem under the condition that the Peccei-Quinn symmetry is respected to extremely high standard. We explore a class of gauge theories that accommodate a high-quality axion, known as the Barr-Seckel models, paying special attention to the cosmology of topological defects. In models with domain wall number equal to unity, we show that axion strings with winding number larger than one can always be decomposed into a number of unit-winding axion strings and pure gauge strings. This mechanism enables the axion string-wall network to be destroyed timely to render a viable cosmology. The subsequent decay of gauge strings into gravitational waves generically produces a double-plateau in frequency space allowing the mechanism to be tested by upcoming experiments.

   hep-phastro-ph.CO3 citations
2. 02*

   Quantum field theory treatment of oscillations of Dirac neutrinos in external fields

   Maxim Dvornikov (IZMIRAN)🇷🇺

   We study neutrino oscillations in external fields using the approach based on the quantum field theory (QFT). Neutrinos are virtual particles in this formalism. Neutrino mass eigenstates are supposed to be Dirac fermions. We consider two cases of external fields: the neutrino electroweak interaction with background matter and the interaction with an external magnetic field owing to the presence of the transition magnetic moment. The formalism used involves the dressed propagators of mass eigenstates in external fields. In the matter case, finding of these propagators for Dirac neutrinos has certain difficulties compared to the Majorana particles considered previously. These difficulties are overcome by regularizing the effective potential of the neutrino interaction with matter. The QFT formalism application to the spin-flavor precession also encounters certain peculiarities in the Dirac case compared to the Majorana one. They are related to the observability of right polarized Dirac neutrinos. We derive the matrix elements and the probabilities for Dirac neutrinos interacting with both types of external fields. In case of the spin-flavor precession, we obtain the small QFT contribution to the probabilities in addition to the prediction of the quantum mechanical approach.

   hep-phhep-thAnnals Phys.(2026)·3 citations
3. 03*

   WIMP Shadows: Phenomenology of Secluded Dark Matter in Three Minimal BSM Scenarios

   Mattia Di Mauro🇮🇹 · Yanhan Wang🇺🇸

   We present a comprehensive study of secluded dark matter (DM) $\chi$, where the relic abundance is set by annihilations into lighter dark mediators $\varphi$ that couple only feebly to the Standard Model (SM). In contrast to canonical WIMPs, which are now strongly constrained by direct and indirect searches, secluded models still achieve the observed relic abundance via thermal freeze-out into hidden-sector mediators, while predicting highly suppressed present-day signals. We analyze three minimal models: (i) a $U(1{)}_X$ gauge boson ($A^{\prime }$) with kinetic mixing; (ii) a scalar DM candidate $S$ with a scalar mediator $K$ that has a trilinear vertex; and (iii) a Dirac fermion $\chi$ whose mass arises from a Higgs-mixed singlet $H_p$. For each model we derive annihilation and scattering rates in both WIMP-like and secluded regimes, and solve the Boltzmann equations: a single-species equation for the WIMP case and a coupled $\chi$-$\varphi$ system for the secluded case to account for possible early departure of the mediator from thermal equilibrium with the SM bath. In this regard, we provide explicit lower limits on the portal coupling $ϵ$ required to keep the mediator in thermal equilibrium with the SM bath and to ensure mediator decay before BBN. We show that for portal couplings $ϵ\ll 10^{-3}$ the relic density is dominantly controlled by DM annihilation into mediator pairs, while spin-independent scattering lies well below current limits and remains viable even for future experiments approaching the irreducible neutrino background floor. Indirect constraints are typically weak due to $p$-wave suppression, off-resonance $s$-channels, and cascade spectra controlled by ${ϵ}^2$. Finally, we highlight the most promising collider tests, which remain sensitive despite tiny portal couplings.

   hep-phastro-ph.HEhep-thPRD(2026)·10 citations
4. 04*

   Quantum Information at the Electron-Ion Collider

   Kun Cheng🇺🇸 · Tao Han🇺🇸 · Sokratis Trifinopoulos🇨🇭

   We investigate quantum-information-theoretic observables in electron-proton scattering at the Electron-Ion Collider (EIC). Our analysis focuses on entanglement and magic, two complementary indicators of non-classicality in quantum states. We show that while unpolarized and longitudinally polarized beams yield unentangled separable outcomes, transverse beam polarization enables the generation of entangled and non-stabilizer states. This result holds for both elastic and deep inelastic electron-proton scattering in QED. In the deep inelastic regime, the degree of quantum correlation is governed by the transversity parton distribution functions, providing a novel perspective on spin dynamics within QCD. These results establish the EIC as a promising environment for generating entangled and non-stabilizer states in high-energy physics, and they highlight opportunities for future lepton-hadron colliders to extend such studies into new kinematic domains.

   hep-phnucl-thquant-ph28 citations
5. 05*

   Towards theory constraints on ultralight dark matter from quantum gravity

   Gabriel Assant🇩🇪 · Astrid Eichhorn🇩🇪 · Benjamin Knorr🇩🇪

   Ultralight scalar dark matter may couple to the Standard Model through dimension-five operators that contain the field-strength tensors of the gauge interactions. Recent progress in nuclear clocks is projected to increase the sensitivity to such couplings by several orders of magnitude. Future experimental constraints may even have Planck-scale sensitivity, calling for a study of such couplings in a framework that includes quantum gravity. We take a first step towards providing the theoretical constraints on such couplings that arise in asymptotically safe gravity. We find evidence that such couplings vanish in asymptotically safe gravity and are also not generated in a perturbative quantum-gravity regime that describes quantum gravity as an effective field theory.

   hep-phgr-qchep-thJHEP(2026)·6 citations
6. 06*

   Recurrence Relations and Dispersive Techniques for Precision Multi-Loop Calculations

   A. Aleksejevs🇨🇦 · S. Barkanova🇨🇦 · A. I. Davydychev🇨🇦

   Ab initio predictions of two-loop electroweak contributions to observables are increasingly essential for precision collider experiments, yet their evaluation remains very challenging. We connect recurrence techniques and dispersive method in order to evaluate complex multi-loop Feynman diagrams. By expressing multi-point Passarino-Veltman functions in a two-point basis and using shifted space-time dimensions with recurrence relations, we minimize the number of required dispersive integrals. This approach reduces computation time and enables a precise and efficient analysis of one- and two-loop diagrams.

   hep-phhep-thPRD(2026)·0 citations
7. 07*

   The Feynman path integral formulation of non-dispersive Airy wave packets and their applications to the heavy meson mass spectra and ultra-cold neutrons

   Paul Ferrante (North Carolina State University)🇺🇸 · Connor Donovan (North Carolina State University)🇺🇸 · Chueng-Ryong Ji (North Carolina State University)🇺🇸

   We demonstrate the non-spreading behavior of Airy wave packets utilizing the Feynman path integral formulation of a linear potential, the Airy functions' zeros correspondence to heavy-meson mass spectroscopy, and their implications to the eigenstates of ultra-cold neutrons in Earth's gravitational field. We derive the linear kernel, and utilize the Feynman path integral time evolution to show that Airy function wave packets are non-dispersive in free space. We then model the confining contribution to 1S - 2S heavy meson mass gaps as a 1+1D absolute linear potential and look at the correspondence of the Airy function zeros. In doing so, we predicted the confining contribution to the mass gap of heavy mesons with a good accuracy when compared to calculations performed in the light front. Furthermore, we used these Airy function solutions to model the quantum states of a neutron under Earth's gravity. We show that the measured heights of a neutron can be modeled by the zeros of the Airy function, and compare to experimental data and predictions utilizing the WKB approximation.

   hep-phquant-phInt.J.Theor.Phys.(2026)·0 citations
8. 08*

   Thermal nature of confining strings

   Sebastian Grieninger🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Eliana Marroquin🇺🇸

   We investigate the quantum statistical properties of the confining string connecting a static fermion-antifermion pair in the massive Schwinger model. By analyzing the reduced density matrix of the subsystem located in between the fermion and antifermion, we demonstrate that as the interfermion separation approaches the string-breaking distance, the overlap between the microscopic density matrix and an effective thermal density matrix exhibits a pronounced, narrow peak, approaching unity at the onset of string breaking. This behavior reveals that the confining flux tube evolves toward a genuinely thermal state as the separation between the charges grows, even in the absence of an external heat bath. In other words, one cannot tell whether a reduced state of the subsystem arises from a surrounding heat bath or from entanglement with the rest of the system. The entanglement spectrum near the critical string-breaking distance exhibits a rapid transition from the dominance of a single state describing the confining electric string towards a strongly entangled state containing virtual fermion-antifermion pairs. Our findings establish a quantitative link between confinement, entanglement, and emergent thermality, and suggest that string breaking corresponds to a microscopic thermalization transition within the flux tube.

   hep-phhep-lathep-thnucl-th+1PRD(2026)·11 citations
9. 09*

   Symmetry Constraints on Pion Valence Structure

   Xiaobin Wang🇨🇳 · Lei Chang🇨🇳 · Minghui Ding🇨🇳 · Khepani Raya🇪🇸 · Craig D. Roberts🇨🇳

   The profile of the pion valence quark distribution function (DF) remains controversial. Working from the concepts of QCD effective charges and generalised parton distributions, we show that since the pion elastic electromagnetic form factor is well approximated by a monopole, then, at large light-front momentum fraction, the pion valence quark DF is a convex function described by a large-$x$ power law that is practically consistent with expectations based on quantum chromodynamics.

   hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2026)·4 citations
10. 10*

    Primordial Black Hole Formation and Multimessenger Signals in a Complex Singlet Extension of the Standard Model

    Fa Peng Huang🇨🇳 · Chikako Idegawa🇨🇳 · Aidi Yang🇨🇳

    We investigate the formation of primordial black holes (PBHs) induced by a first-order electroweak phase transition in a realistic renormalizable framework, the complex singlet extension of the Standard Model. We perform a quantitative analysis of the PBH abundance and identify parameter regions consistent with current microlensing constraints. Furthermore, we show that the same parameter space predicts observable stochastic gravitational waves within the sensitivities of future space-based detectors, as well as a sizable deviation in the Higgs triple coupling that can be probed at future lepton colliders. Our results highlight a comprehensive multimessenger framework in which PBH, gravitational wave, and collider observations can jointly test the dynamics of a strongly first-order electroweak phase transition in the early Universe.

    hep-phPRD(2026)·6 citations
11. 11*

    OmniLearned: A Foundation Model Framework for All Tasks Involving Jet Physics

    Wahid Bhimji🇺🇸 · Chris Harris🇺🇸 · Vinicius Mikuni🇯🇵 · Benjamin Nachman🇺🇸

    Foundation models use large datasets to build an effective representation of data that can be deployed on diverse downstream tasks. Previous research developed the OmniLearn foundation model for jet physics, using unique properties of particle physics, and showed that it could significantly advance discovery potential across collider experiments. This paper introduces a major upgrade, resulting in the OmniLearned framework. This framework has three new elements: (1) updates to the model architecture and training, (2) using over one billion jets used for training, and (3) providing well-documented software for accessing all datasets and models. We demonstrate OmniLearned with three representative tasks: top-quark jet tagging with the community Delphes-based benchmark dataset, b-tagging with ATLAS full simulation, and anomaly detection with CMS experimental data. In each case, OmniLearned is the state of the art, further expanding the discovery potential of past, current, and future collider experiments.

    hep-phPRD(2026)·37 citations
12. 12*

    Analytic QCD: Recent Results

    A.V. Kotikov🇷🇺 · I.A. Zemlyakov🇨🇱

    We present a brief overview of analytical QCD, focusing primarily on a less common form of the analytical coupling A_{\rm MA}(Q^2), which is particularly convenient for Q^2\sim\Lambda^2. This form has been extensively used in recent studies of the (polarized) Bjorken sum rule and the Gross-Llewellyn Smith sum rule.

    hep-phPoS(2026)·0 citations
13. 13*

    Searching for long-lived axion-like particles via displaced vertices at the HL-LHC

    Chong-Xing Yue🇨🇳 · Xin-Yang Li🇨🇳 · Shuo Yang🇨🇳 · Mei-Shu-Yu Wang🇨🇳

    Axion-like particles (ALPs) are well-motivated extensions of the standard model (SM) that appear in numerous new physics scenarios. In this paper, we concentrate on searches for long-lived ALPs predicted by the photophobic scenario at the HL-LHC with the center-of-mass energy $\sqrt{s}=14$ TeV and the integrated luminosity $\mathcal{L}=$ $3$ ab${}^{-1}$. We consider the process $pp\to \gamma a$ with the ALP $a$ decaying into a pair of displaced charged leptons and perform a detailed analysis of two types of signals: ${\pi }^{+}{\pi }^{-}\gamma E{/}_T$ and ${\ell }^{+}{\ell }^{-}\gamma E{/}_T$. For the ${\pi }^{+}{\pi }^{-}\gamma E{/}_T$ signal, we find that the prospective sensitivities of the HL-LHC can reach $g_{aWW}\in [8.72\times 10^{-3},6.42\times 10^{-2}]$ TeV${}^{-1}$ for the ALP mass $m_a\in [4,10]$ GeV. While for the ${\ell }^{+}{\ell }^{-}\gamma E{/}_T$ signal, the HL-LHC can probe a broader parameter space, with the sensitivities covering $m_a\in [4,10]$ GeV and $g_{aWW}\in [4.17\times 10^{-3},2.00\times 10^{-1}]$ TeV${}^{-1}$. These long-lived searches complement some previous prompt decay studies from LEP and LHC experiments, extending the parameter space explored by the LHCb collaboration. Our results show that the HL-LHC has significant potential to probe long-lived ALPs via their displaced vertex signatures.

    hep-phEPJC(2025)·5 citations
14. 14*

    Relaxed constraints for dark matter with axial coupling to a dark photon

    X. G. Wang🇦🇺 · A. W. Thomas🇦🇺

    We present a new model of the dark sector involving Dirac fermion dark matter, with axial coupling to a dark photon which provides a portal to Standard Model particles. In the non-relativistic limit, this implies that the dominant effective operator relevant to direct detection is ${\mathcal{O}}_8$. The resulting event rate for direct detection is suppressed by either the dark matter velocity or the momentum transfer. In this scenario there are much wider regions of the dark parameter space that are consistent with all of the existing constraints associated with thermal relic density, direct detection and collider searches.

    hep-phastro-ph.COhep-exPRD(2026)·3 citations
15. 15*

    Diffractive deep inelastic scattering in the dipole picture: the $q\bar{q}g$ contribution in exact kinematics

    Abhiram Kaushik🇫🇮 · Heikki Mäntysaari🇫🇮 · Jani Penttala🇺🇸

    We compute the $q\bar{q}g$ contribution to the diffractive structure functions in high-energy deep inelastic scattering. The obtained result corresponds to a finite part of the next-to-leading-order contribution to the diffractive cross section. Previous phenomenological applications have included this contribution only in the high-$Q^2$ or high-$M_X^2$ limits in the case of a soft gluon, and we numerically demonstrate that these existing estimates do not provide a good approximation for the full $q\bar{q}g$ contribution. Furthermore, we demonstrate that in addition to the soft gluon contribution, there is an equally important soft quark contribution to the diffractive structure functions at high $Q^2$.

    hep-phnucl-thPRD(2026)·4 citations
16. 16*

    Probing the nonstrange quark star equation of state with compact stars and gravitational waves

    Shu-Peng Wang🇨🇳 · Zhen-Yan Lu🇨🇳 · Zhi-Jun Ma🇨🇳 · Rong-Yao Yang🇨🇳 · Jian-Feng Xu🇨🇳 · Xiangyun Fu🇨🇳

    A recent study shows that incorporating a new term into the thermodynamic potential density, as required by the thermodynamic consistency criterion, can effectively resolve the thermodynamic inconsistency problems of the conventional perturbative QCD model. This additional term plays a crucial role in resolving inconsistencies at relatively low densities and becomes negligible at extremely high densities. Within this revised perturbative QCD model, we find that if we require only that the energy per baryon of up-down ($ud$) quark matter exceeds 930 MeV so as not to contradict the standard nuclear physics, the maximum mass of an $ud$ quark star allowed by the revised perturbative QCD model can reach up to 2.17 $M_{\odot }$. From this perspective, the observed 2.14 $M_{\odot }$ pulsar PSR J0740+6620 may be an $ud$ quark star. However, if we further impose the constraint that the tidal deformability of a 1.4 $M_{\odot }$ $ud$ quark star must be consistent with the GW170817 event, the maximum mass allowed by the revised perturbative QCD model would decrease to no more than 2.08 $M_{\odot }$. Consequently, our results suggest that the compact object with a mass of 2.50-2.67 $M_{\odot }$, as observed in the GW190814 event, cannot be an $ud$ quark star, according to the revised perturbative QCD model.

    hep-phastro-ph.HEnucl-thPRD(2025)·2 citations
17. 17*

    Probing the existence of a new charged vector boson decaying into heavy neutral leptons using ultra-peripheral heavy ion collisions at ATLAS

    Y.M. Oviedo-Torres🇨🇱 · Sebastian Tapia · J. Zamora-Saa🇨🇱

    In this paper we explore the potential of Ultra-peripheral Collisions at the LHC to investigate new physics, focusing on the production of new charged vector bosons $V^{\pm }$ that decay into heavy neutral leptons $N_L$ in the context of the Vector Scotogenic Model. We show that the ATLAS experiment, searching for dilepton+met final states via UPCs of lead ions, can directly probe the existence of new charged vector bosons in the 5 GeV $<M_{V^{\pm }},M_{N_L}<$ 105 GeV mass range. Our analysis identifies regions in the parameter space where the signal can be distinguished from the background with high statistical significance. Within this mass range, ATLAS can exclude at 95\% C.L. specific ($M_{V^{\pm }}$, $M_{N_L}$) mass scenarios such as (30 GeV, 20 GeV), (30 GeV, 10 GeV) and (20 GeV, 10 GeV). In a discovery scenario, ATLAS could reach a significance of 5$\sigma$ for (20 GeV, 10 GeV). In addition, we show that HL-LHC with proton-proton UPCs could explore higher mass ranges, specifically 100 GeV $<M_{V^{\pm }},M_{N_L}<$ 350 GeV. We find that the HL-LHC can exclude this mass range with 95\% C.L., covering a larger parameter space than previous SUSY searches, and most scenarios can achieve a discovery significance of 5$\sigma$.

    hep-phEPJC(2026)·0 citations
18. 18*

    Finite-size effects and scaling properties of chiral and baryon-number fluctuations

    Győző Kovács🇵🇱 · Pok Man Lo🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    An effective chiral model is introduced to illustrate finite-size effects, incorporating the standard zero-mode treatment, momentum-space discretization, and gradient effects modeled via a prescribed finite-volume profile. The fluctuations of the chiral order parameter and the net-baryon number, as well as their scaling properties, are investigated near a critical point and a first-order transition in finite-size systems. The finite-volume effects on the Binder cumulant and the kurtosis are shown along the phase boundary and the approximate freeze-out line, respectively. Phenomenological implications on fluctuation observables are pointed out and explained.

    hep-phPRD(2026)·1 citation
19. 19*

    Associated production of a $W$-boson and a charm meson at NNLO in QCD

    Terry Generet🇬🇧 · Rene Poncelet🇵🇱 · Miha Muškinja🇸🇮

    The production of heavy-flavor hadrons in association with a vector boson in proton-proton collisions is a powerful probe for studying Quantum Chromodynamics and the content of protons. In this article, we provide, for the first time, differential predictions through NNLO for the production of $W^{\pm }{D}^{(\ast )\mp }$ final states. The results are compared to recent ATLAS measurements, and the sensitivity to the strange content of the proton is investigated by PDF profiling. The results are found to be promising for including $W^{\pm }{D}^{(\ast )\mp }$ measurements in proton-proton collisions in PDF fits.

    hep-phJHEP(2026)·8 citations
20. 20*

    Dijets with a large rapidity separation in the next-to-leading order BFKL formalism for searches of large extra dimensions at colliders

    Anatolii Iu. Egorov🇷🇺 · Victor T. Kim🇷🇺 · Viktor A. Murzin🇷🇺 · Vadim A. Oreshkin🇷🇺

    Search for the gravity with large extra dimensions at collider energies is considered in the trans-Planckian eikonal regime, i.e., when $\sqrt{\hat{s}}\gg M_D\gg \sqrt{-\hat{t}}$. Here $\hat{s}$ and $\hat{t}$ are the Mandelstam variables of colliding parton-parton system and $M_D$ is the Planck mass scale in the space-time with compactified $n_D$ extra dimensions. A relevant observable for this regime may be the cross section of high-mass ($M_{jj}\sim \sqrt{\hat{s}}\gg M_D$) dijet production with a large rapidity separation. Then the standard model background should be calculated within the next-to-leading logarithmic (NLL) approximation of Lipatov-Fadin-Kuraev-Balitsky (BFKL) formalism of quantum chromodynamics (QCD) suitable for $\sqrt{\hat{s}}\gg \sqrt{-\hat{t}}\gg {\Lambda }_{\mathrm{QCD}}$. In this work the signal of the large extra dimension gravity as well as the NLL BFKL QCD background are estimated for the high-luminosity Large Hadron Collider (HL-LHC) and future colliders such as FCCpp and CEPC-SppC.

    hep-phPRD(2026)·2 citations
21. 21*

    Higgs Inflation: Particle Factory

    Tammi Chowdhury🇨🇦 · Leah Jenks🇺🇸 · Edward W. Kolb🇺🇸 · Evan McDonough🇨🇦

    We study cosmological gravitational particle production (CGPP) in Higgs inflation, wherein the inflaton is a scalar field with quartic self-coupling $\lambda$ and a nonminimal coupling to gravity $\xi$, and which may, but need not be, the Higgs boson of the Standard Model (SM). We find an explosive particle production peaked on a characteristic comoving wavenumber $k\sim {\xi }^{2/3}aH$ with a peak occupation number that scales with $\xi$. This new peak in production can easily dominate over the conventional (minimally coupled inflation) CGPP even for modest values of $\xi$. The results apply for a wide range of $\xi$, e.g., as low as $\xi =10$, which can be realized for the Standard Model Higgs given suitable RG flow of the quartic coupling. We discuss implications for late time relics such as dark matter.

    hep-phastro-ph.COgr-qchep-thJHEP(2026)·2 citations
22. 22*

    Higgs-Boson Decays: Updates

    Emanuele Bagnaschi🇮🇹 · Lisa Biermann🇨🇭 · Michael Spira🇨🇭

    In this contribution, new developments for the Standard Model Higgs-boson decays will be summarized. This addresses extensions of the grids used by {\tt Hdecay} to implement finite NLO mass effects for $H\to gg$ as well as explicit numbers for the branching fraction for the strange-Yukawa induced part of $H\to s\bar{s}$ together with the related uncertainties. In addition, first results of the strong and weak Dalitz decays of the Higgs-boson decays $H\to s\bar{s}+g/\gamma$ are presented. The Dalitz decays define the separation between the Yukawa-induced part and the continuum, that is not induced by the strange-Yukawa coupling, and thus pave the way towards a solid determination of the strange-Yukawa coupling at future $e^{+}{e}^{-}$ colliders, but will also be relevant for solid bounds on the strange-Yukawa coupling at the LHC.

    hep-phhep-exSciPost Phys.Comm.Rep.(2026)·4 citations
23. 23*

    Particle-level transformers for 95 GeV Higgs boson searches at future $e^{+}{e}^{-}$ Higgs factories

    Yabo Dong🇨🇳 · Manqi Ruan🇨🇳 · Kun Wang🇨🇳 · Haijun Yang🇨🇳 · Jingya Zhu🇨🇳

    Motivated by several mild excesses around 95~GeV, we investigate the prospects for a light scalar $S$ produced via Higgsstrahlung, $e^{+}{e}^{-}\to Z({\mu }^{+}{\mu }^{-})S$, at future $e^{+}{e}^{-}$ Higgs factories. We take the CEPC as a benchmark, with a center-of-mass energy of $\sqrt{s}=240$ GeV and an integrated luminosity of $L=20{\mathrm{ab}}^{-1}$. We focus on the decay modes $S\to {\tau }^{+}{\tau }^{-}$ and $S\to b\bar{b}$. To maximize sensitivity, we employ the particle-level transformer networks Particle Transformer (ParT) and its more-interactive variant MIParT, which exploit the features of all reconstructed objects and their correlations. For a representative signal benchmark, this approach improves the expected statistical precision on the signal strength by factors of 2.3 in the ${\tau }^{+}{\tau }^{-}$ channel and 1.4 in the $b\bar{b}$ channel compared to a cut-based analysis. Within the flipped Next-to-Two-Higgs-Doublet Model (N2HDM-F), the CEPC can measure the signal strength with a statistical precision down to 1.0% in the ${\tau }^{+}{\tau }^{-}$ channel and 0.69% in the $b\bar{b}$ channel using MIParT. It can achieve a $5\sigma$ discovery for ${\mu }_{\tau \tau }^{ZS}>1.6\times 10^{-2}$ or ${\mu }_{bb}^{ZS}>5.0\times 10^{-3}$, and reach 1% precision for ${\mu }_{\tau \tau }^{ZS}>0.93$ or ${\mu }_{bb}^{ZS}>0.14$. These gains are expected to qualitatively carry over to other future lepton colliders such as FCC-ee and the ILC. Our results demonstrate the potential of particle-level machine-learning techniques to strengthen light Higgs searches at future $e^{+}{e}^{-}$ Higgs factories.

    hep-phPRD(2026)·3 citations
24. 24*

    Weak interactions and the gravitational collapse

    Domenec Espriu🇪🇸

    The chart of nuclei could be enlarged with a branch describing neutron stars that are huge nuclei of a few solar masses held together by gravity force and sustained by the pressure due to the degenerate Fermi sea. We contend in this manuscript that yet another branch could be added: objects with a large weak charge, with masses around $10^{-3}$ solar masses and having radii of a few meters, very compact, only slightly larger than their Schwarzchild radius, and sustained by the pressure generated by the weak force due to $Z$ exchange. This interaction, insignificant in normal neutron stars, could become dominant when ultrahigh densities are reached due to the action of gravity and lead to stable configurations if the appropriate conditions are met. They would constitute a physical realization of the equation of state proposed by Zeldovich some decades ago.

    hep-phastro-ph.SRgr-qchep-th0 citations
25. 25*

    Leading large $N_c$ contributions to Lepton Number Violating Meson Decays

    Andrea Donini🇪🇸 · Marcela González🇨🇱 · Martin Hirsch🇪🇸 · Nicolás A. Neill🇨🇱

    Lepton number violating meson decays, such as $M_1^{-}\to M_2^{+}{\ell }_1^{-}{\ell }_2^{-}$, provide constraints on $d=9$ $\Delta L=2$ operators. RGE-improved bounds on the Wilson coefficients of these operators have been presented in the literature, taking into account perturbative QCD one-loop corrections and the corresponding operator mixing. Here, we present for the first time the contribution of connected diagrams to the hadronic matrix elements $⟨M_2|{\mathcal{O}}_h|M_1⟩$. These diagrams, usually overlooked under the assumption that $⟨M_2|{\mathcal{O}}_h|M_1⟩\sim ⟨M_2|J_{q_3{q}_4}|0⟩\times ⟨0|J_{q_1{q}_2}|M_1⟩\gg ⟨M_2|J_{q_3{q}_2}\times J_{q_1{q}_4}|M_1⟩$, can give indeed a significant contribution to the matrix element. Including these connected diagrams is but the first step towards a full non-perturbative computation of the long-range QCD effects in these operators, that should be performed using lattice field theory techniques. However, connected diagrams represent the leading order in the $1/N_c$ expansion of the QCD non-perturbative effects and thus our work can be understood as a realistic, first approximation to a complete calculation of the long-range part of the matrix elements.

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

    Impact of dim-6 $\nu$SMEFT operators on low-scale leptogenesis

    Kaori Fuyuto🇯🇵 · Julia Harz🇩🇪 · Sascha Weber🇩🇪

    We investigate the impact of higher-dimensional operators on low-scale leptogenesis (LG) via oscillations of right-handed neutrinos within the neutrino-extended Standard Model Effective Field Theory ($\nu$SMEFT) and discuss the connection to neutrinoless double beta decay ($0\nu \beta \beta$). Focusing on a dimension-six, lepton number conserving operator, we explore how new interactions can significantly alter the production and equilibration dynamics of right-handed neutrinos. We derive the relevant quantum kinetic equations incorporating both renormalizable and non-renormalizable interactions and perform a comprehensive numerical analysis for benchmark scenarios in both the oscillatory and overdamped regimes. Our results reveal that even in the absence of explicit lepton number violation by the operator, it can enhance or suppress the baryon asymmetry of the universe (BAU) by several orders of magnitude, depending on the EFT scale. We further connect these effects to predictions for $0\nu \beta \beta$ decay, demonstrating that the same operator can lead to enhanced decay rates, potentially within reach of the next generation of experiments. Our findings indicate that the observation of $0\nu \beta \beta$ could rule out a large part of the parameter space for successful low-scale LG within the $\nu$SMEFT, implying low RHN masses and low reheating temperatures.

    hep-phJHEP(2026)·3 citations
27. 27*

    A Precise ${\alpha }_s$ Determination from the R-improved QCD Static Energy

    Jose M. Mena-Valle🇪🇸 · Vicent Mateu🇪🇸 · Pablo G. Ortega🇪🇸

    The strong coupling ${\alpha }_s$ is determined with high precision from fits to lattice QCD simulations on the static energy. Our theoretical setup relies on R-improving the three-loop fixed-order prediction for the static energy by removing its $u=1/2$ renormalon and summing up the associated large (infrared) logarithms which, in combination with radius-dependent renormalization scales (called profile functions) extends the validity of perturbation theory to distances up to $\sim 0.5$fm. Furthermore, we resum large ultrasoft logarithms to N${}^3$LL accuracy using renormalization group evolution. We have checked that the standard four-loop R-evolution treats N${}^4$LL and higher remnants in a non-symmetric way, hence we also account for this potential bias. Our estimate of the perturbative uncertainty is based on a random scan over the parameters specifying the profile functions and the treatment of R-evolution. We also devise a method to statistically combine into a single dataset results from independent simulations which use different lattice spacing and cover various ranges, which can be used to carry out fits in a much faster way. We explore the dependence of the extracted ${\alpha }_s$ value on the smallest and largest distances included in the dataset, on how R-evolution is treated, on how the fit is performed, and on the accuracy of ultrasoft resummation. From our final analysis, after evolving to the $Z$-pole we obtain ${\alpha }_s^{(n_f=5)}(m_Z)=0.1166\pm 0.0009$, compatible with the world average with similar incertitude.

    hep-phhep-latJHEP(2026)·2 citations
28. 28*

    Heavy Quark Energy Loss in the Hybrid Model

    Andrea Beraudo🇮🇹 · Jean F. Du Plessis🇺🇸 · Daniel Pablos🇪🇸 · Krishna Rajagopal🇺🇸

    Heavy quarks offer an invaluable hard probe of the droplets of quark gluon plasma (QGP) formed in heavy ion collisions at the LHC and RHIC. Given their large mass, they are predominantly produced in hard scattering processes at the earliest moment of a collision and given their rarity they almost never annihilate with a heavy antiquark subsequently. This means that they experience, and probe, the entire history of the expanding, cooling, droplet of QGP from hydrodynamization through hadronization. Quantitative measurements of heavy quark final state observables therefore give us access to information about the transport properties of QGP as well as about medium modifications of hadronization. To date, the Hybrid strong/weak coupling Model of jet quenching has not included any implementation of the heavy-quark sector, which has made it impossible to confront its predictions with measurements of heavy quark and jet observables together, in a unified fashion. Here, we extend the Hybrid Model to investigate heavy quark observables for the first time. We introduce a strongly-coupled calculation of heavy-quark energy loss with the correct behavior when the heavy quarks are either ultrarelativistic or non-relativistic, Gaussian momentum broadening, and recombination of heavy quarks with medium partons using a local color neutralization model of hadronization. We compare our results for the suppression $R_{\mathrm{AA}}$ and azimuthal anisotropies $v_2$ of B- and D-mesons and ${\Lambda }_c$ baryons, the $R_{\mathrm{AA}}$ of B-tagged jets, as well as baryon-to-meson ratios, with available experimental data from ALICE, ATLAS and CMS.

    hep-phnucl-exnucl-thJHEP(2026)·6 citations
29. 29*

    Super-Leading Logarithms in Top-Quark Pair Production at Hadron Colliders

    Upalaparna Banerjee🇮🇳 · Romy Grünhofer🇩🇪 · Matthias König🇩🇪 · Yibei Li🇩🇪 · Matthias Neubert🇺🇸 · Josua Scholze🇩🇪

    To date, the appearance and resummation of "super-leading" logarithms in hadron-hadron collisions has been studied only for massless parton states. We extend the formalism to include an arbitrary number of massive final states. We derive the corresponding anomalous dimension and identify an additional Coulomb phase that gives rise to a new source of super-leading logarithms. We then perform a systematic leading-logarithmic resummation of these contributions for $2\to M$ processes. Finally, we analyze the numerical impact in partonic scattering processes for $t\bar{t}$ production, including a treatment of the Sommerfeld enhancement observed near threshold.

    hep-phJHEP(2026)·6 citations
30. 30*

    Study of Neutron Star Properties under the Two-Flavor Quark NJL Model

    Chunran Zhu · Bolin Li🇨🇳

    The Equation of State (EOS) of matter within neutron stars is a central topic in nuclear physics and astrophysics.This study investigates hadron-quark hybrid stars by integrating the density-dependent DDME2 relativistic mean-field model for hadronic matter with a two-flavor Nambu-Jona-Lasinio (NJL) model for quark matter.A quintic polynomial interpolation is employed to construct a smooth ($C^2$ continuity) and thermodynamically consistent crossover between the phases.We systematically explore the parameter space to reconcile the tension between the high stiffness required by massive pulsars and the softness demanded by tidal deformability and radius constraints.Our analysis demonstrates that to simultaneously satisfy the mass measurement of PSR J0740+6620 and the compact radius constraints from NICER (e.g., PSR J0437-4715), the hadron-quark crossover must initiate in the vicinity of nuclear saturation density.This result suggests that the early percolation of quark degrees of freedom is a necessary feature to accommodate current multi-messenger observations.

    ↳ astro-ph.HEgr-qchep-phnucl-th0 citations
31. 31*

    Two Shades of Quark Color: Parallel Canons across the Cold War Divide

    Vitaly Pronskikh🇺🇸

    The introduction of the color quantum number is conventionally narrated as a linear progression from the quark-model statistics paradox to quantum chromodynamics (QCD). This paper challenges that teleology by arguing that "color" emerged as two conceptually distinct constructs during the Cold War. The first, originating with Han and Nambu and culminating in QCD, conceived of color as a local gauge charge, the source of a fundamental force mediated by gluons. The second, developed at the Joint Institute for Nuclear Research (JINR) in Dubna, treated color as a hidden, three-valued label--a statistical and structural property within a composite, S-matrix-inflected hadron model. We trace these parallel narratives, linking the Dubna approach to a holist epistemology that prioritizes observable amplitudes and global constraints, and the QCD approach to a reductionist program grounded in micro-dynamics. A case study of Fermilab's E-36 experimental chain (1970--78) shows how an observables-first design-tuned to S-matrix and Regge constraints on forward elastic scattering--performed robustly within its natural domain but was ultimately discontinued amid declining theoretical interest and involvement. The subsequent hegemony of QCD retroactively projected its gauge-theoretic conception of color onto history, erasing this epistemic diversity. We conclude that the marginalization of Dubna's structural color was not merely a political outcome of the Cold War but a result of deep ontological and philosophical divergences, advocating for a domain-sensitive pluralism in the historiography of particle physics.

    ↳ physics.hist-phhep-exhep-phhep-th0 citations
32. 32*

    Symmetry Energy of 2+1-flavor dense quark matter from perturbative QCD

    Isabella Danhoni🇺🇸 · Yumu Yang🇺🇸 · Mauricio Hippert🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸

    The symmetry energy expansion was developed to connect isospin symmetric matter probed in nuclear experiments to asymmetric matter found in neutron stars. Using the isospin asymmetry derived from the Gell-Mann-Nishijima formula, we derive the symmetry energy expansion for quark matter that has unique properties compared to hadronic matter. To test our methods, we use perturbative Quantum Chromodynamics (pQCD) calculations at next-to-leading-order, where realistic quark masses can be included. We find that pQCD at electroweak equilibrium is not isospin symmetric but rather obtains a small skewness term in the symmetry energy expansion. We predict that if equations of state for nuclear matter must match pQCD results, then a non-monotonic dip in the symmetry energy would appear.

    ↳ nucl-thastro-ph.HEhep-phPRC(2026)·9 citations
33. 33*

    Definition and Treatment of Systematic Uncertainties in High Energy Physics and Astrophysics

    Pekka K. Sinervo🇨🇦 · C.M

    Systematic uncertainties in high energy physics and astrophysics are often significant contributions to the overall uncertainty in a measurement, in many cases being comparable to the statistical uncertainties. However, consistent definition and practice is elusive, as there are few formal definitions and there exists significant ambiguity in what is defined as a systematic and statistical uncertainty in a given analysis. I will describe current practice, and recommend a definition and classification of systematic uncertainties that allows one to treat these sources of uncertainty in a consistent and robust fashion. Classical and Bayesian approaches will be contrasted.

    ↳ hep-exhep-pheConf C030908 (2003) TUAT004·2 citations
34. 34*

    Dirac spectrum in the chirally symmetric phase of a gauge theory. I

    Matteo Giordano🇭🇺

    I study the consequences of chiral symmetry restoration for the Dirac spectrum in finite-temperature gauge theories in the two-flavor chiral limit, using Ginsparg--Wilson fermions on the lattice. I prove that chiral symmetry is restored at the level of the susceptibilities of scalar and pseudoscalar bilinears if and only if all these susceptibilities do not diverge in the chiral limit $m\to 0$, with $m$ the common mass of the light fermions. This implies in turn that they are infinitely differentiable functions of $m^2$ at $m=0$, or $m$ times such a function, depending on whether they contain an even or odd number of isosinglet bilinears. Expressing scalar and pseudoscalar susceptibilities in terms of the Dirac spectrum, I use their finiteness in the symmetric phase to derive constraints on the spectrum, and discuss the resulting implications for the fate of the anomalous $\mathrm{U}(1{)}_A$ symmetry in the chiral limit. I also discuss the differentiability properties of spectral quantities with respect to $m^2$, and show from first principles that the topological properties of the theory in the chiral limit are characterized by an instanton gas-like behavior if $\mathrm{U}(1{)}_A$ remains effectively broken.

    ↳ hep-lathep-phhep-th5 citations
35. 35*

    Dirac spectrum in the chirally symmetric phase of a gauge theory. II

    Matteo Giordano🇭🇺

    I discuss the consequences of the constraints imposed on the Dirac spectrum by the restoration of chiral symmetry in the chiral limit of gauge theories with two light fermion flavors, with particular attention to the fate of the anomalous $\mathrm{U}(1{)}_A$ symmetry. Under general, physically motivated assumptions on the spectral density and on the two-point eigenvalue correlation function, I show that effective $\mathrm{U}(1{)}_A$ breaking in the symmetric phase requires specific spectral features, including a spectral density effectively behaving as $m^2\delta (\lambda )$ in the chiral limit, a two-point function singular at zero, and delocalized near-zero modes, besides an instanton gas-like behavior of the topological charge distribution. I then discuss a $\mathrm{U}(1{)}_A$-breaking scenario characterized by a power-law divergent spectral peak tending to $O(m^4)/|\lambda |$ in the chiral limit and by a near-zero mobility edge, and argue that the mixing of the approximate zero modes associated with a dilute gas of topological objects provides a concrete physical mechanism producing the required spectral features, and so a viable mechanism for effective $\mathrm{U}(1{)}_A$ breaking in the symmetric phase of a gauge theory.

    ↳ hep-latcond-mat.dis-nnhep-phhep-th3 citations
36. 36*

    Comprehensive Inclusion of Higher-order Ca${}^{+}$ Isotope Shifts in the King's Plot Yields an Order Improvement on the $e^{-}$-$n$ Coupling Limit

    Vaibhav Katyal🇮🇳 · A. Chakraborty🇮🇳 · B. K. Sahoo🇮🇳

    By critically evaluating higher-order nonlinear effects to the isotope shifts (ISs) in the low-lying transition frequencies of the singly charged calcium ion, stringent constraint on the electron-neutron coupling due to a hypothetical boson describing physics beyond the Standard Model is inferred. It shows an order magnitude difference compared to the previously reported limit demonstrating importance of higher-order effects in the analysis of nonlinearity in the King's plot. The first-order IS parameters and enhancement factor ($D$) were evaluated using two complementary approaches in the relativistic coupled-cluster theory framework: namely finite-field (FF) and analytical response (AR) approaches. Extraction of the second-order IS parameters in the FF approach show numerical instabilities, so they are determined in the AR approach. Comparison of these factors with previous calculation shows substantial differences in the magnitudes. However, $D$ values from both the FF and AR approaches display excellent agreement. We also show explicitly roles of electron correlation effects in the evaluation of $D$ values accurately.

    ↳ physics.atom-phastro-ph.SRhep-phnucl-ex+10 citations
37. 37*

    Comment on "Chiral symmetry restoration, the eigenvalue density of the Dirac operator, and the axial U(1) anomaly at finite temperature"

    Matteo Giordano🇭🇺

    Aoki, Fukaya, and Taniguchi claim that both the spectral density of the Dirac operator at the origin and the topological susceptibility must vanish identically for sufficiently small but nonzero quark mass $m$ in the chirally symmetric phase of quantum chromodynamics with two light quark flavors, under certain technical assumptions on the spectrum and on the dependence of observables on $m$. I argue that a crucial step of their proof is not justified, and the validity of these conclusions should be reassessed. In an additional note I refute the objections raised by S. Aoki and H. Fukaya in their reply to my comment. I show that both the $m^2$-analyticity assumption they invoke against my arguments, and the very claim that these arguments criticize, imply that all local gluonic correlators are independent of the light-quark mass at small mass. This behavior, however, is not observed in quantum chromodynamics. I then show that their claim of having found a mistake in my arguments is baseless.

    ↳ hep-lathep-phhep-thPRD(2026)·3 citations
38. 38*

    Black Hole Cold Brew: Fermi Degeneracy Pressure

    Wei-Xiang Feng🇨🇳 · Hai-Bo Yu🇺🇸 · Yi-Ming Zhong🇨🇳

    We investigate the dynamical instability of a self-gravitating thermal system in the quantum regime, where Fermi degeneracy pressure becomes significant. Using a truncated Fermi-Dirac distribution and solving the Tolman-Oppenheimer-Volkoff equation, we identify marginally stable configurations following Chandrasekhar's criterion. While Fermi pressure stabilizes a system against gravitational collapse in Newtonian gravity, in general relativity it can instead drive the instability, enabling collapse even at low temperatures. In the low-temperature limit, the critical mass is independent of the boundary temperature. We discuss implications for the formation of massive black holes in the early Universe through the gravothermal collapse of dark matter.

    ↳ gr-qcastro-ph.COhep-phPRD(2026)·1 citation
39. 39*

    Low-lying baryon resonances from lattice QCD

    Colin Morningstar🇺🇸

    Calculating the properties of baryon resonances from quantum chromodynamics requires evaluating the temporal correlations between hadronic operators using integrations over field configurations weighted by a phase associated with the action. By formulating quantum chromodynamics on a space-time lattice in imaginary time, such integrations can be carried out non-perturbatively using a Markov-chain Monte Carlo method with importance sampling. The energies of stationary states in the finite volume of the lattice can be extracted from the temporal correlations. A quantization condition involving the scattering $K$-matrix and a complicated ``box matrix'' also yields a finite-volume energy spectrum. By appropriately parametrizing the scattering $K$-matrix, the best-fit values of the $K$-matrix parameters are those that produce a finite-volume spectrum which most closely matches that obtained from the Monte Carlo computations. Results for the $\Delta$ resonance are presented, and a study of scattering for energies near the $\Lambda (1405)$ resonance is outlined, showing a two pole structure. The prospects for applying this methodology to the Roper resonance are discussed.

    ↳ hep-lathep-phnucl-thActa Phys.Polon.B(2026)·0 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.