Mon·Apr 13, 2026Monday·April 13, 2026

1. 01*

   Probing Higgs and Top Interactions through the Muon Lens at multi-TeV Muon Colliders

   Tisa Biswas🇮🇳 · Anindya Datta🇮🇳 · Barbara Mele🇮🇹

   We investigate the sensitivity of a future 10 TeV muon collider to dimension-6 operators in the Standard Model Effective Field Theory (SMEFT), focusing on Higgs and top quark production processes. The analysis includes two-fermion and four-fermion operators that induce electroweak vector and axial-vector interactions, as well as dipole, scalar, and tensor interactions involving muons. Many of these operators are only weakly constrained or difficult to probe at the LHC due to limited sensitivity and large SM backgrounds. We study the processes ${\mu }^{+}{\mu }^{-}\to Zh$, ${\mu }^{+}{\mu }^{-}\to {\mu }^{+}{\mu }^{-}h$, ${\mu }^{+}{\mu }^{-}\to t\bar{t}$, and ${\mu }^{+}{\mu }^{-}\to t\bar{t}h$, exploiting the energy-enhanced SMEFT effects at multi-TeV scales accessible to a muon collider. Using detailed simulations that incorporate differential information and angular distributions, we derive projected bounds on the relevant Wilson coefficients. We find that a 10 TeV muon collider can strengthen existing limits on muon-Higgs-gauge and muon-top interactions by up to an order of magnitude, surpassing even FCC-ee projections. Finally, we interpret these bounds in the context of representative UV scenarios, including models with vector-like lepton and scalar leptoquarks, highlighting the potential of a muon collider to probe new physics at scales well beyond the LHC reach.

   hep-phhep-exJHEP(2026)·0 citations
2. 02*

   Axion Quality in Warped Extra-Dimension

   Kiwoon Choi🇰🇷 · Chang Hyeon Lee🇰🇷 · Chang Sub Shin🇰🇷

   We investigate the axion quality problem in warped extra-dimensional models in which the QCD axion arises as the Wilson-line mode of a five-dimensional $U(1)$ gauge field compactified on an $S^1/{\mathbb{Z}}_2$ orbifold. Higher-dimensional gauge invariance severely constrains possible sources of Peccei--Quinn symmetry breaking, implying that non-QCD contributions to the axion potential are predominantly generated by nonlocal effects mediated by $U(1)$-charged fields propagating along the compact dimension. We systematically compute these contributions and examine how both the warped geometry and the orbifold fixed points (branes) affect the resulting axion quality. Finally, we classify the parametric suppression of the induced axion potential, thereby identifying the conditions under which warped extra-dimensional axions can achieve sufficiently high quality.

   hep-phhep-th7 citations
3. 03*

   A numerical implementation of the NLO DIS structure functions in the dipole picture

   Henri Hänninen🇫🇮 · Heikki Mäntysaari🇫🇮 · Jani Penttala🇺🇸

   We present a numerical program that evaluates deep inelastic scattering (DIS) structure functions at next-to-leading order (NLO) accuracy in the dipole picture. In this numerical implementation the NLO DIS impact factors with massive quarks are written in a form that ensures a stable numerical evaluation of the DIS cross sections.

   hep-phnucl-thSciPost Phys.Codeb.(2026)·1 citation
4. 04*

   Probing High-Quality Axions with Gravitational Waves

   Ruiyu Zhou🇨🇳 · Jin-Wei Wang🇨🇳 · Ligong Bian🇨🇳

   We present a systematic study of gravitational wave (GW) signals from phase transitions and topological defects in a unified high-quality axion framework. The gauged $U(1{)}_g$ symmetry forbids any bias term that could lift the vacuum degeneracy, restricting the theory to the phenomenologically viable case $N_{\mathrm{DW}}=1$. Requiring the axion to account for the observed dark matter (DM) abundance and satisfy the high-quality condition constrains the gauge symmetry-breaking scale to $f_g\in [1.6\times 10^{11},10^{16}]\mathrm{GeV}$ for the QCD axion, leading to a well-defined band of GW signals, part of which is consistent with current pulsar timing array observations. Two-step first-order phase transitions are common in this framework, with the lower-scale transition generating GWs with $f^{\mathrm{peak}}\gtrsim \mathcal{O}(10^7)\mathrm{Hz}$. For axion-like realizations, generic post-inflation models predict GW spectra that are nearly degenerate with the QCD axion case. We conclude that GWs alone cannot distinguish between these scenarios, highlighting the need for complementary probes.

   hep-ph2 citations
5. 05*

   Classical and spin polarizabilities of singly heavy baryons within heavy baryon chiral perturbation theory

   Zi-Jun Li🇨🇳 · Zhan-Wei Liu🇨🇳 · Ping Chen🇨🇳

   We present a systematic study of the electromagnetic and spin polarizabilities of spin-1/2 singly charmed baryons at $\mathcal{O}(p^4)$ within the framework of heavy baryon chiral perturbation theory. Our results show that the higher-order corrections to the electric polarizability are small, while those to the magnetic polarizability are relatively larger due to the small mass splitting of singly charmed baryons and are closely related to transition magnetic moments. Furthermore, we find that the spin polarizabilities of singly charmed baryons, except for ${\gamma }_{M1M1}$, are much smaller than those of the nucleons. We have also calculated the polarizabilities for singly bottom baryons, with the results showing generally larger values than those of singly charmed baryons.

   hep-ph1 citation
6. 06*

   Hadronic form factors in QCD and the incompleteness problem in the time-like region

   Enrique Ruiz Arriola🇪🇸 · Pablo Sanchez-Puertas🇪🇸 · Wojciech Broniowski🇵🇱

   Hadronic form factors fulfill dispersion relations and superconvergence sum rules for their spectral density as genuine imprints of QCD. We show several instances where these conditions are flagrantly violated due to the lack of information in the region above the largest known resonance mass and below the onset of perturbative QCD. We propose to use radial Regge trajectories to fill this gap and examine the consequences of such a minimal spectral hadronic ansatz. We illustrate the results with the pion charge form factor.

   hep-phActa Phys.Polon.Supp.(2026)·3 citations
7. 07*

   A Levinson's theorem for particle form factors

   Francesco Rosini🇮🇹 · Simone Pacetti🇮🇹

   We present and demonstrate a version of Levinson's theorem especially dedicated to the asymptotic behavior of form factor phases. Indeed, as required by analyticity, form factors are multi-valued complex functions of a square four-momentum defined in the complex plane with a cut along the positive real axis. Their phases evaluated on the upper edge of this cut, i.e., on the time-like region, tend asymptotically to integer multiples of $\pi$ radians. The Levinson's theorem establishes a univocal relation between such multiples and properties of form factors related to the dynamics of the electromagnetic interaction of the corresponding hadrons.

   hep-phmath-phmath.MP0 citations
8. 08*

   Constraining new physics in charm quark associated Higgs boson production events using the Standard Model effective field theory approach

   Nordin Breugelmans🇧🇪 · Felix Heyen🇧🇪 · Jorgen D'Hondt🇳🇱 · Michael Tytgat🇧🇪 · Gerrit Van Onsem🇧🇪

   As the search for observable deviations from the Standard Model of particle physics remains to be of significant interest, effective field theory (EFT) continues to be a popular method to parametrize such effects. In this work, a first-time investigation is performed of the unique capability of measurements of charm quark associated Higgs boson production (cH) in proton-proton collisions at the CERN Large Hadron Collider to constrain a set of dimension-six EFT operators. The phenomenology of these operators is discussed and a proposed analysis strategy is presented, with a focus on $\mathrm{H}\to \mathrm{Z}{\mathrm{Z}}^{\ast }\to 4\mu$ decays, using a generic detector simulation that is parametrized to reflect the response of the CMS detector at the LHC. From this, expected 95% CL upper limits are derived for the Wilson coefficients of individual operators by considering yield and shape effects in the spectra of the four-muon invariant mass $m_{4\mu }$ and leading jet transverse momentum $p_T$. Scenarios with simultaneous contributions from two operators are also considered. Finally, potential analysis improvements that may be implemented in an experimental context are outlined.

   hep-phJHEP(2026)·0 citations
9. 09*

   Probing Solar Symmetrons with Direct Detection

   Hannah Banks🇬🇧 · Anne-Christine Davis🇬🇧 · Luca Visinelli🇮🇹

   We provide the first investigation of the solar production of symmetrons, a well-motivated class of screened scalar fields with density dependent couplings to the Standard Model, and their subsequent absorption in underground direct detection experiments. We compute the flux of symmetrons produced through photon conversion in the magnetic field of the solar tachocline, and constrain the resulting luminosity to not exceed 3% of the observed solar output. Even under the conservative assumption that production occurs only in the tachocline, this criterion yields robust astrophysical bounds on previously uncharted regions of symmetron parameter space, and predicts a keV-scale symmetron spectrum at Earth. We then derive the corresponding absorption signal in liquid xenon detectors, where symmetrons can interact with electrons through both conformal and disformal couplings. Using binned data from XENONnT, we obtain new direct-detection limits that are complementary to the solar luminosity constraint, further tightening the viable symmetron parameter space. Our results demonstrate that the Sun provides a testable, previously unexploited, source of symmetrons, and highlight that the interplay of astrophysical and laboratory searches offers a powerful strategy for probing screened scalar theories.

   hep-phastro-ph.COgr-qc0 citations
10. 10*

    A General Prescription for Spurion Analysis of Non-Invertible Selection Rules

    Ling-Xiao Xu🇮🇹

    We formulate a general prescription for spurion analysis in particle-physics models whose selection rules are described by commutative non-invertible fusion algebras. The construction applies to fusion algebras containing non-invertible basis elements that need not be self-conjugate, thereby allowing us to systematically track coupling constants in arbitrary particle scattering processes at tree and loop orders, but without assuming faithful realization of the fusion algebra, or no other quantum numbers for dynamical particles. This unifies and streamlines the previous analysis of near-group fusion algebras and of the ${\mathbb{Z}}_M/{\mathbb{Z}}_2$ fusion algebras, and supports the broader viewpoint that the non-invertible selection rules often admit auxiliary descriptions using lifted Abelian groups with a structured set of explicit breaking terms.

    hep-phhep-th4 citations
11. 11*

    CMB signatures of gravity-mediated dark radiation in $\mathbf{\Delta }{\mathbf{N}}_{\mathrm{eff}}$

    Anish Ghoshal🇬🇧 · Sk Jeesun🇨🇳 · Kazunori Kohri🇯🇵

    Measurement of $N_{\mathrm{eff}}$ in the CMB (Cosmic Microwave Background) observations, like Planck 2018 and BBN (Big Bang Nucleosynthesis) has already set stringent constraints on the interaction strength of light particles beyond the Standard Model (BSM). Despite such negligible couplings of such BSM particles to the visible sector, they are inevitably produced in the early universe through gravity-mediated processes. If a sizable density of light particles survives around CMB formation, they may act as dark radiation (DR) contributing to $N_{\mathrm{eff}}$ at CMB epoch. In this work, we study the production of such light BSM particles through the gravity-mediated scatterings in an effective field theory (EFT) setup assuming that all non-gravitational couplings of the BSM particle are negligible. Since the production is sensitive to the spin of the produced particle, we perform a concrete analysis for two representative cases: scalar dark Higgs DR and vector dark photons DR.Using the Planck 2018 observations, we find constraints on the reheating temperature ($T_{\mathrm{RH}}$) and background equation of state ($w_{\Phi }$) during reheating in such scenarios featuring dark Higgs and dark photon. A comparative discussion involving gravity-mediated production of Dirac right-handed neutrinos (${\nu }_R$) and light axion-like particles (ALP) is also presented. Finally, for completeness, we also analyze the scenario where the production occurs through a generic spin-2 mediator characterized by an effective scale $\Lambda$ delineating the parameter space that is currently ruled out from Planck-2018 and can be probed by the future CMB experiments like LiteBird, Simon Observatory, CMB-S4, CMB-HD.

    hep-phastro-ph.COhep-th0 citations
12. 12*

    Threshold Top-Quark Pair-Production: Cross Sections and Key Uncertainties

    Maria Vittoria Garzelli🇩🇪 · Giovanni Limatola🇩🇪 · Sven-Olaf Moch🇩🇪 · Matthias Steinhauser🇩🇪 · Oleksandr Zenaiev🇩🇪

    We study theoretical uncertainties in predicting top-quark pair-production near threshold at the LHC using the non-relativistic QCD framework. We include variations in the top-quark mass and width, the strong coupling ${\alpha }_s$, renormalization and factorization scales, and parton distribution functions, as well as uncertainties from the color-singlet and octet Green's functions that describe quasi-bound toponium formation. These uncertainties are compared with those from standard fixed-order QCD predictions, and implications for ATLAS and CMS analyses are discussed. For the LHC at 13 TeV center-of-mass energy, the integral of the top-quark pair invariant-mass distribution from 340 to 350 GeV is 11.67 pb with ${}_{-1.47}^{+1.43}$ pb uncertainty. The corresponding excess after subtracting the POWHEG-BOX result is 4.15 pb with the same uncertainties.

    hep-ph3 citations
13. 13*

    The four-loop non-singlet splitting functions in QCD

    Thomas Gehrmann🇨🇭 · Andreas von Manteuffel🇩🇪 · Vasily Sotnikov🇨🇭 · Tong-Zhi Yang🇨🇳

    The scale evolution of parton distributions is governed by splitting functions. We compute the four-loop splitting functions in perturbative QCD that control the evolution of quark non-singlet distributions. We confirm previous partial results and obtain, for the first time, fully analytic expressions for all non-singlet contributions at this order. These allow us to extract the analytic form of the four-loop virtual and rapidity anomalous dimensions entering logarithmic resummation. We provide precise numerical representations of the splitting functions suitable for parton evolution.

    hep-phhep-th9 citations
14. 14*

    Tidal Response of Compact Objects

    Sumanta Chakraborty🇮🇳 · Paolo Pani🇮🇹

    The tidal response of compact objects provides a powerful probe of their internal structure and of the surrounding gravitational field. We provide a comprehensive and unified overview of tidal effects in black holes, neutron stars, and exotic compact objects, with emphasis on both static and dynamical responses to external fields, encoded in Love numbers and dissipation numbers. We discuss the vanishing of static bosonic Love numbers for black holes in vacuum General Relativity, their modifications in alternative theories, in non-standard models of compact objects, and in the presence of matter, as well as their role in testing deviations from Einstein's theory and environmental effects. A fundamental distinction between bosonic and fermionic perturbations is highlighted, as the latter yield nonzero static Love numbers even for black holes in General Relativity. For neutron stars, we overview the dependence of tidal Love numbers on the equation of state, the emergence of quasi-universal relations, and the impact of rotation, nonlinearities, and dynamical effects. Exotic compact objects typically feature nonvanishing static tidal Love numbers -- a striking observational signature that differentiates them from black holes. We further review how tidal effects influence the gravitational-wave signals from binary inspirals, and explore their implications for gravitational-wave astronomy. In particular, we stress their significance for current and future detectors as tools to test General Relativity, constrain the nuclear equation of state, and probe the fundamental nature of compact objects and their environments.

    ↳ gr-qcastro-ph.HEhep-phhep-th23 citations
15. 15*

    Genericness of quantum damping of cosmological shear in modified loop quantum cosmology

    Wen-Cong Gan🇨🇳 · Leila L. Graef🇧🇷 · Rudnei O. Ramos🇧🇷 · Gustavo S. Vicente🇧🇷 · Anzhong Wang🇺🇸

    In arXiv:2603.18175, the authors argue, based on numerical studies of particular cases, that the quantum damping of cosmological shear in a modified loop quantum cosmological model (mLQC-I) that was recently found in arXiv:2510.14021 is not generic and that the universe never becomes truly classical. In this brief Note, we revisit these claims by carefully examining the underlying assumptions and the class of initial conditions considered. We show that the examples analyzed in arXiv:2603.18175 correspond to configurations that do not represent physically admissible collapsing Bianchi I universes, as they involve mixed expanding-contracting directions and lead to effectively lower-dimensional post-bounce geometries. Restricting to physically relevant initial conditions corresponding to genuine three-dimensional contraction, we find that the quantum damping of cosmological shear is a robust dynamical feature. This conclusion is supported by both numerical and perturbative analyses, which demonstrate that the post-bounce evolution admits an isotropic attractor, with anisotropies decaying exponentially and independently of the matter content, provided that the weak energy condition is satisfied. We further outline a plausible post-bounce mechanism for the onset of classicalization.

    ↳ gr-qcastro-ph.COhep-phhep-th2 citations
16. 16*

    New limits on the Pauli forbidden transitions in 12C nuclei obtained with the complete Borexino dataset

    Borexino collaboration · D. Basilico · G. Bellini · J. Benziger · R. Biondi · B. Caccianiga · A. Caminata · A. Chepurnov · D. D Angelo · A. Derbin · A. Di Giacinto · V. Di Marcello and 61 other authors

    The Pauli exclusion principle (PEP) was tested for nucleons in ${}^{12}\mathrm{C}$ nuclei using the Borexino dataset from 2007 to 2021. %the complete Borexino detector data. The approach consists of searching for $\gamma$-quanta, neutrons, protons, as well as electrons and positrons emitted in non-Paulian transitions of nucleons from the $1P_{3/2}$ shell to the filled $1S_{1/2}$ shell. Due to the uniquely low background level, the large mass, and long measurement time of the Borexino detector, the most stringent experimental constraints to date on the lifetime of the ${}^{12}\mathrm{C}$ nucleus with respect to PEP-forbidden transitions were obtained: $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{C}}+\gamma )\ge 1.1\times 10^{32}$ y, $\tau ({}^{12}\mathrm{C}\to {}^{11}\tilde{\mathrm{B}}+p)\ge 1.0\times 10^{31}$ y, $\tau ({}^{12}\mathrm{C}\to {}^{11}\tilde{\mathrm{C}}+n)\ge 2.0\times 10^{31}$ y, $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{N}}+e^{-}+\widetilde{{\nu }_e})\ge 6.4\times 10^{30}$ y and $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{B}}+e^{+}+{\nu }_e)\ge 6.6\times 10^{30}$ y (90\% C.L.). The upper limits on the relative strengths for the non-Paulian electromagnetic, strong, and weak transitions have been obtained: ${\delta }_{\gamma }^2\le 1.0\times 10^{-57}$, ${\delta }_N^2\le 7.0\times 10^{-61}$ and ${\delta }_{\beta }^2\le 9.6\times 10^{-36}$, all at 90\% C.L..

    ↳ nucl-exhep-exhep-phEPJC(2026)·0 citations
17. 17*

    Towards better nuclear charge radii

    István Angeli🇭🇺 · Dimiter L. Balabanski🇷🇴 · Paraskevi Dimitriou🇦🇹 · Dipti🇺🇸 · Kieran T. Flanagan🇬🇧 · Georgi Georgiev🇫🇷 · Mikhail Gorchtein🇩🇪 · Paul Gùeye🇺🇸 · Fabian Heiße🇩🇪 · Andreas Knecht🇨🇭 · Kei Minamisono🇺🇸 · Wilfried Nörtershäuser🇩🇪 and 7 other authors

    Nuclear charge radii constitute a physical observable of growing significance across multiple subdisciplines of physics and related fields. Their determination relies on a combination of complementary experimental techniques and advanced theoretical frameworks. Current recommended values are informed by the outcomes of several independent working groups, each employing distinct methodological approaches and evaluation strategies. The present effort is directed toward a more precise and reliable extraction of charge radii, as well as the development of a modern, transparent, and methodologically robust compilation of recommended values.

    ↳ nucl-exhep-phnucl-thphysics.atom-ph4 citations
18. 18*

    Bounding axion dark energy

    Gary Shiu🇺🇸 · Flavio Tonioni🇮🇹 · Hung V. Tran🇺🇸

    We study cosmological solutions of (pseudo)scalar theories with periodic potentials, in the presence of arbitrary cosmological fluids -- including a cosmological constant of either sign. Independently of the initial misalignment angle and field velocity, we derive an analytic bound that the axion mass parameter and decay constant fulfill as the universe decreases its acceleration rate, finding a natural application in models of thawing quintessence. As a first application, we illustrate the analytic handle our bound provides in bounding axion dark energy, after observational inputs from DESI and various supernovae data sets are taken into account. As a second application, we argue that our analytic bounds in combination with proposed quantum gravity constraints on axions exclude vast regions of parameter space. The combined constraints push the axion masses to be much larger than the Hubble scale, in tension with basic models of axion quintessence.

    ↳ astro-ph.COhep-phhep-th5 citations
19. 19*

    High-energy neutrino constraints on primordial black holes as dark matter

    Mainak Mukhopadhyay🇺🇸 · Joaquim Iguaz Juan🇺🇸

    Primordial black holes (PBHs) are one of the most appealing dark matter candidates over a wide range of masses and abundances. This broad parameter space has been constrained by a variety of observational probes. In this work, for the first time, we use data from high-energy neutrino telescopes, like IceCube and ANTARES, to constrain sub-asteroid mass ($\lesssim 10^{18}\mathrm{g}$) Schwarzschild PBHs with extended mass functions. We derive limits from the diffuse high-energy neutrino flux produced by the direct evaporation of PBHs, as well as from the transient signatures associated with PBHs passing in the vicinity of the Earth. While our bounds are slightly weaker than existing constraints from gamma-ray observations, they provide an independent and complementary probe based on observational high-energy neutrino data. We further show that future detectors such as IceCube-Gen2 and KM3NeT can significantly improve these constraints, potentially excluding PBHs with masses up to $\sim \mathrm{few}\times 10^{18}\mathrm{g}$ composing the entirety of dark matter.

    ↳ astro-ph.HEastro-ph.COhep-ph3 citations
20. 20*

    Multi-soft theorems for cosmological correlators: Background wave method for scalars & gravitons

    Farman Ullah🇮🇳

    Cosmological soft theorems (or consistency relations) provide a powerful probe for the physics of inflation. These relations rely on minimal assumptions and hold very generally. Consequently, any violation of these relations would rule out a large class of inflationary models. For instance, a violation of the scalar soft theorem (or consistency relation) would rule out all attractor single-field inflation models and instead point toward either multi-field dynamics or a non-attractor phase. In this paper, we derive tree-level multi-soft theorems, at leading order in the soft expansion, for both scalar and tensor correlation functions. Our analysis employs the background-wave method, in which the effect of long-wavelength modes is captured by an appropriate spatial coordinate rescaling. In addition, we systematically incorporate soft-exchange contributions, including tensor exchanges in scalar correlators and scalar exchanges in tensor correlators.

    ↳ hep-thgr-qchep-ph0 citations
21. 21*

    Nonequilibrium crossover in the supercritical region from quench dynamics

    Zi-Qiang Zhao🇨🇳 · Zhang-Yu Nie🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    Distinguishing different subphases in the supercritical region is an important issue in statistical physics and condensed matter physics. Traditional approaches rely mainly on static thermodynamic response functions or equilibrium correlation functions, which are essentially limited to quasistatic processes. In this paper, we investigate the evolution behavior of a system after a rapid quench from the perspective of nonequilibrium dynamics within a holographic model. We find that, using the time at which inhomogeneous structures appear most rapidly, we can define a supercritical crossover curve based on the pure phase separation process. In addition, the uniform invasion phenomenon induced by topological defects persists in the supercritical region, and the invasion velocity exhibits a clear turning point as a function of the quench endpoint. This turning point can define another new nonequilibrium supercritical crossover line that simultaneously incorporates the effects of both symmetry breaking and phase separation. Unlike the classical Widom line or Frenkel line, these two new crossover lines contain both thermodynamic information and dynamical information, reflecting the dynamical nature of the supercritical region under nonequilibrium conditions. This work provides a novel nonequilibrium dynamical approach for characterizing supercritical subphases.

    ↳ cond-mat.stat-mechhep-phhep-thPLB(2026)·2 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.