Fri·Mar 6, 2026Friday·March 6, 2026

1. 01*

   Improved supernova bounds on CP-even scalars: cooling and decay constraints

   Melissa Joseph🇺🇸 · Samuel Liebersbach🇺🇸 · Anirudhan A. Madathil🇺🇸 · Gustavo Marques-Tavares🇺🇸

   Supernovae provide among the most powerful probes of weakly-coupled new particles in the MeV mass range, where laboratory experiments lose sensitivity. In this work, we derive improved supernova constraints on CP-even scalars mixing with the Higgs boson, combining an updated production rate calculation, which improves the cooling bound by more than an order of magnitude, with new decay-based constraints from the galactic 511~keV positron flux and energy deposition in low-energy Type~II-P supernovae. Together, these constraints probe mixing angles as small as $\sin \theta \sim 10^{-9}$, more than five orders of magnitude below existing collider bounds. We also extend our analysis to a hadrophilic scalar model, constraining Yukawa couplings down to $y_N\sim 10^{-10}$. Our results demonstrate that the combination of astrophysical and collider probes covers over nine orders of magnitude in coupling for these classes of models, probing a large region of parameter space motivated by dark matter considerations.

   hep-ph4 citations
2. 02*

   50 Years of SUSY and SUGRA, circa 1974-2024, and Future Prospects

   Pran Nath🇺🇸

   The development in the early seventies of supersymmetry, in the mid-seventies of gauge supersymmetry and supergravity, and in the early eighties of gravity mediated breaking of supersymmetry and of supergravity grand unification have led to remarkable progress in the pursuit of unification of fundamental interactions of particle physics. They have also led to the intertwining of particle physics, cosmology, and strings. Since supersymmetry and supergravity are manifest in the low energy limit of superstring below the Planck scale, experimental test of them are of interest regarding the validity of the superstring itself. For that reason, over the past decades, after the advent of supersymmetry and SUGRA models, there have been sustained experimental searches for supersymmetry at colliders, in precision experiments, and in astrophysical and cosmological data. The SUSY and SUGRA models have also had deep impact on theories related to inflation, dark matter, and dark energy. The purpose of this article is to provide a view from the bridge of these developments over the past fifty years circa 1974-2024.

   hep-phhep-thInt.J.Mod.Phys.A(2026)·2 citations
3. 03*

   The effect of charm quark on the QCD chiral phase diagram

   Fei Gao🇨🇳 · Yuepeng Guan🇨🇳 · Shinya Matsuzaki🇨🇳

   We study the influence of charm-quark dynamics on the chiral phase structure of Quantum Chromodynamics (QCD) using the recently developed miniDSE scheme for the Dyson-Schwinger equations. By comparing the quark and gluon propagators in the $2+1$- and $2+1+1$-flavor setups within the same truncation scheme, we qualify the impact of the charm-quark loop on the QCD phase diagram. Our results show that the charm quark has only a mild effect on the crossover boundary, which remains almost unchanged within the present setup. The most visible effect is a small shift of the critical endpoint (CEP) toward lower baryon chemical potential, by approximately $3\%$. The present result provides a controlled estimate of the charm-loop effect within the same miniDSE truncation. It indicates that heavy-flavor contributions may become relevant when aiming at precision studies of the CEP location.

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

   Exploring Nucleon Structure and the Proton Mass Problem through Holographic QCD

   Jiali Deng🇨🇳 · Defu Hou🇨🇳

   Understanding the internal structure of the proton-including the distributions of quarks and gluons and their contributions to proton properties such as mass-remains a central challenge in quantum chromodynamics (QCD). While quark generalized parton distributions (GPDs) have been studied extensively, a unified approach that simultaneously extracts quark parton distribution functions (PDFs), gravitational form factors (GFFs), and gluon GPDs from experimental constraints is still lacking. Moreover, the role of gluons in proton mass generation, particularly through the trace anomaly mechanism, requires deeper theoretical and phenomenological exploration. In this study, we begin by extracting quark GPDs in protons using a parameterization method based on the electromagnetic form factors provided by Light-Front Holographic QCD (LFHQCD), from which we derive both quark PDFs and their GFFs. We then extend this approach to model gluon GPDs. Our calculations show consistency with experimental data and lattice QCD results and successfully reproduce soft Pomeron behavior. Furthermore, we investigate near-threshold $J/\psi$ production using gauge/string duality to quantify the contribution of the trace anomaly to the proton mass. Our results demonstrate that the parameterization method provides a consistent framework for describing both quark and gluon structure, bridging GPDs, PDFs, and GFFs. The analysis of $J/\psi$ production confirms that the trace anomaly contributes significantly ($\sim 24\%$) to the proton mass, with the calculated cross-section dependence on momentum transfer $t$ in agreement with experimental observations. This work advances the understanding of proton structure by integrating quark and gluon degrees of freedom and elucidating the origin of proton mass within QCD.

   hep-phnucl-thPRD(2026)·4 citations
5. 05*

   Magnetic moments of strange hidden-bottom pentaquarks and the role of spin flavor correlations

   Pallavi Gupta🇮🇳 · Vikash kumar Garg🇮🇳

   We investigate the magnetic moments of strange hidden-bottom pentaquark states within the constituent quark model, considering both molecular and compact configurations. The system with quark content $qqqb\bar{b}$ ($q=u,d,s$) is analyzed in three configurations: a baryon-meson molecular form $(\bar{b}{q}_1)(b{q}_2{q}_3)$, a diquark-diquark-antiquark structure $(b{q}_1)(q_2{q}_3)\bar{b}$, and a diquark-triquark configuration $(b{q}_1)(\bar{b}{q}_2{q}_3)$. Negative-parity states with $J^P=1/2^{-}$, $3/2^{-}$, and $5/2^{-}$ are studied for strangeness $\mathcal{S}=-1,-2,-3$. For the dominant spin couplings, the two compact configurations yield identical or numerically very close magnetic moments. This indicates that the magnetic properties are governed primarily by the global spin-flavor structure and heavy-quark suppression effects rather than by the specific clustering of quarks. A systematic suppression with increasing strangeness and a clear spin hierarchy are observed across all configurations. Due to the large bottom-quark mass, heavy-quark contributions are strongly suppressed, and the magnetic moments are dominated by light-strange spin correlations. These results provide useful theoretical benchmarks for future experimental and lattice studies of exotic multiquark states.

   hep-phhep-thPTEP(2026)·0 citations
6. 06*

   Critical fluctuation patterns and anisotropic correlations driven by temperature gradients

   Lijia Jiang🇨🇳 · Tao Yang🇨🇳 · Jun-Hui Zheng🇨🇳

   Studies of QCD phase transition signals are often conducted under spatially uniform temperature conditions. However, the influence of spatial temperature gradients on the signals emerging at the phase interface in the fireball generated by heavy-ion collisions has not yet been fully explored. Based on an Ising-like effective potential, we study the locally equilibrated systems with temperature gradients. In a 2D disk geometry, the low-energy fluctuation spectrum is explicitly resolved into radial and angular momentum modes. The nonlocal correaltions of singular eigen-mode exhibits strong anisotropy, which are long-ranged along isotherms but suppressed radially due to the thermal geometry of the system. Unlike homogeneous systems where the zero-momentum mode dominates, correlations in such inhomogeneous system result from the superposition of a series of zero and non-zero angular momentum modes with comparable contributions. We extract the singular angular momentum modes and establish their connection to experimentally observable anisotropic flow. We find azimuthally sensitive observables may offer a previously unexplored avenue for detecting the QCD phase transition.

   hep-ph0 citations
7. 07*

   On the robustness of the indirect determination of the width of the detected Higgs boson

   Panagiotis Stylianou🇨🇾 · Georg Weiglein🇩🇪

   The indirect determination of the total width of the detected Higgs boson that is carried out by the experimental collaborations at the LHC relies on the assumption that the coupling modifiers for the on-shell and off-shell couplings are the same. However, physics beyond the Standard Model affecting the on-shell and off-shell regions differently could invalidate this assumption, so that the actual width of the detected Higgs boson could be larger than the bounds obtained under this assumption. Relaxing the assumption and investigating different types of extensions of the Standard Model, we analyse under which conditions a larger total width of the detected Higgs boson is compatible with all experimental and theoretical constraints. For the considered scenarios of scalar extensions with an additional state contributing as a resonance or at the loop level, we find that the indirect bounds obtained by ATLAS and CMS remain valid over large parts of the parameter space, with the exception of parameter regions where the additional particles have relatively small masses. We discuss the potential of experimental searches for new particles to further constrain such scenarios. Based on the existing experimental and theoretical constraints we conclude that relaxing the assumption of equal on-shell and off-shell coupling modifiers that is used in the experimental analyses at the LHC yields an upper bound on the total width of the detected Higgs boson in realistic extensions of the Standard Model that is only weakened by up to a factor of about two compared to the case where this assumption is valid.

   hep-phhep-ex1 citation
8. 08*

   Renormalisation of Chiral Gauge Theories with Non-Anticommuting ${\gamma }_5$ at the Multi-Loop Level

   Matthias Weißwange🇩🇪

   This thesis presents a comprehensive study of the renormalisation of chiral gauge theories in dimensional regularisation (DReg) at the multi-loop level. We employ the mathematically consistent Breitenlohner-Maison/`t~Hooft-Veltman (BMHV) scheme with non-anticommuting ${\gamma }_5$, whose modified algebraic relations induce a spurious violation of gauge and BRST invariance. A central focus is the systematic restoration of the broken symmetry, for which we provide a transparent and fully algorithmic procedure based on the quantum action principle. A major achievement of this work is the complete 4-loop renormalisation of an Abelian chiral gauge theory -- the highest-order application of the BMHV scheme to date. This calculation is made possible by an automated, high-performance computational framework incorporating several optimised algorithms. Our results demonstrate that a rigorous, self-consistent treatment of ${\gamma }_5$ is feasible even at very high loop orders. We further analyse dimensional ambiguities and evanescent details corresponding to different implementations of the regularisation, and identify practically efficient prescriptions for $D$-dimensional fermions and gauge interactions. Building on these insights, we present the complete 1-loop renormalisation of the full Standard Model (SM) in the BMHV scheme, providing a first step towards a fully self-consistent multi-loop renormalisation of the SM and establishing a solid foundation for future high-precision electroweak phenomenology.

   hep-phhep-th2 citations
9. 09*

   Muon collider experiments as electron/positron beam sources: case studies of new light-particle searches

   Yasuhito Sakaki🇯🇵 · Daiki Ueda🇮🇱

   At muon colliders, muon decays naturally produce intense electrons and positrons with unique features, namely high energies, high repetition rates, and small intrinsic uncertainties, that are unavailable at existing accelerator facilities. We quantitatively study the feasibility of extracting such particles in two representative future muon collider designs, IMCC and $\mu$TRISTAN. Using Monte Carlo simulations with the corresponding design parameters, we study the spatial, angular, and energy distributions of decay electrons and positrons in the curved sections of the collider ring. We find that typical deflections of $0.1-10\mathrm{mrad}$ can be achieved even for high-energy electrons carrying large energy fractions ($\simeq 0.6-1.0$) of the muon beam energy, with the ring bending magnets (or magnets providing an equivalent field) effectively serving as a pre-septum magnet, that partially deflects the beam before the main septum magnet, suggesting that the extraction scheme could be practically feasible. Exploiting the distinct beam properties of IMCC and $\mu$TRISTAN, we propose complementary search strategies, missing energy and momentum searches for dark matter at $\mu$TRISTAN and visible-decay searches for axion-like particles and light scalars at IMCC, which probe parameter space beyond the reach of current and other proposed experiments.

   hep-phhep-ex1 citation
10. 10*

    Flavor Democracy Calls for Vector Like Leptons and Quarks

    Burak Dagli🇹🇷 · Saleh Sultansoy🇹🇷 · Ismail Toy🇹🇷

    There are strong arguments favoring the Flavor Democracy hypothesis (or the Democratic Mass Matrix approach) within the Standard Model framework. However, the large mass of the top quark ($m_t>>m_b,m_{\tau }$) poses an obstacle to the functioning of Flavor Democracy in the three SM family scenario. While a fourth Standard Model generation could have provided a natural resolution, this possibility is now almost entirely excluded by precision data on Higgs boson production and decay rates. The Flavor Democracy hypothesis can be elegantly resurrected through the introduction of Vector-Like Leptons (VLLs) and Vector-Like Quarks (VLQs), which naturally accommodate the observed fermion mass hierarchies while remaining consistent with current experimental constraints. Currently, experimental searches for VLLs conducted by the ATLAS and CMS collaborations rely on a highly constrained Restricted Model. This model imposes a mass degeneracy between charged and neutral VLLs within a doublet and assumes the absence of right-handed neutrinos. Consequently, current results are valid only for the restricted model and do not cover a more realistic, general scenario. Therefore, to accurately reflect the physical reality, it is imperative to conduct a comprehensive re-evaluation that incorporates all viable decay channels.

    hep-ph1 citation
11. 11*

    TeV-scale unification of light dark matter and neutrino mass

    Cheng-Wei Chiang🇹🇼 · Shu-Yu Ho🇹🇼 · Van Que Tran🇹🇼

    We demonstrate that TeV-scale heavy neutral leptons (HNLs) responsible for inverse-seesaw neutrino mass generation can simultaneously fix the cosmological abundance and decay properties of dark matter (DM). The spontaneous breaking of lepton number gives rise to a pseudo-Nambu-Goldstone boson that serves as a light DM candidate, whose mass originates from a small explicit symmetry-breaking term. The same HNLs that generate neutrino masses produce the DM via freeze-in and mediate its decay into neutrinos, leading to a tight correlation among neutrino masses, DM relic abundance, and DM lifetime. For collider-accessible TeV-scale HNLs, the observed relic density and lifetime constraints point to sub-GeV DM, yielding observable neutrino signals at JUNO and next-generation detectors such as Hyper-Kamiokande and DUNE. This framework establishes a predictive and experimentally testable link between neutrino mass generation and DM.

    hep-phhep-th1 citation
12. 12*

    Effective vertexes in magnetized quark-gluon plasma

    V. Skalozub🇺🇦

    In quark-gluon plasma (QGP), at high temperatures $T$ the spontaneous generation of color magnetic fields, $b^3(T),b^8(T)\ne 0$ (3, 8 are color indexes), and usual magnetic field $b(T)\ne 0$ happens. Also, the Polyakov loop and related to it the $A_0(T)$ condensate, which is solution to Yang-Mills imaginary time equations, create. Recently, with the new type two-loop effective potential, which generalizes the known integral representation for the Bernoulli polynomials and takes into consideration the magnetic background, these effects were derived. The corresponding effective potential $W(T,b^3,b^8,b,A_0)$ was calculated either in SU(2) gluodynamics or full quantum chromodynamics (QCD). The values of magnetic field strengths at different temperatures were calculated and the mechanism for stabilizing the background due to $A_0(T)$ was also discovered. In present paper, we concentrate on the one-loop quark contributions. In particular, we derive the effective vertexes, which couple magnetic fields and $A_0$. The vertexes result in new specific effects signalling the creation of QGP in heavy ion collision experiments. Key words: spontaneous magnetization, high temperature, asymptotic freedom, effective potential, $A_0$ condensate, effective vertexes.

    hep-ph0 citations
13. 13*

    Axial-vector neutral-current measurements in coherent elastic neutrino-nucleus scattering experiments

    D. Aristizabal Sierra🇨🇱 · Pablo M. Candela🇪🇸 · Valentina De Romeri🇪🇸 · Dimitrios K. Papoulias🇪🇸 · Laura Trincado S🇨🇱

    Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) is predominantly governed by vector neutral-current interactions, with subleading contributions arising from the axial current in nuclei with non-zero ground-state spin. Experimentally, the extraction of axial-current contributions has been so far of little interest, mainly because of the challenges its measurement entail. In this work, we investigate the relative size of the vector and axial components for target materials currently employed by the neutrino and dark matter experimental communities. We identify fluorine-based compounds as the most promising targets for probing the axial-current event rate. Among them, octafluoropropane (${\text{C}}_3{\text{F}}_8$) emerges as a particularly suitable candidate, given its widespread use in spin-dependent dark matter searches and its relevance for upcoming dedicated CE$\nu$NS experiments. Considering both pion decay-at-rest and reactor neutrino fluxes, we show that such measurements can allow an indirect determination of the axial coupling at the $\sim 10\%$ level, depending on flux uncertainties and detector thresholds. We further emphasize that measurements of the axial current will allow to probe spin-dependent new physics scenarios through CE$\nu$NS.

    hep-phhep-exnucl-exnucl-thPRD(2026)·2 citations
14. 14*

    The eV-Scale Sterile Neutrino and Neutrinoless Double Beta Decay

    Priya🇮🇳 · Simran Arora🇮🇳 · B. C. Chauhan🇮🇳

    In short-baseline experiments such as LSND and MiniBooNE, an excess of electron neutrinos has been observed, originating from a muon neutrino beam. To address this anomaly, in the line of many works, we investigate various neutrino mixing schemes involving eV-scale sterile neutrinos alongside three active neutrinos. Using updated experimental and global fit data, we studied neutrinoless double beta decay for three different schemes such as 3+1, 1 + 3, and 2 + 2, which involve one sterile neutrino and three active neutrinos. We have done analysis of these schemes for normal hierarchy (NH) as well as for inverted hierarchy (IH) frameworks, and constrained the sterile neutrino mass in light of current and future neutrinoless double beta decay experiments. The 3+1 scheme is found to be the most viable and at the level of $3\sigma$ the mass of sterile neutrino with respect to the lightest neutrino mass ($m_{\text{lightest}}$) is restricted to $4.75eV$ for the NH and $4.72eV$ for the IH. Additionally, the limits on the sum of four neutrino masses are determined to be $4.81eV$ for the normal hierarchy and $4.78eV$ for the inverted hierarchy. The updated analysis of all these schemes would help us in understanding physics governing neutrinoless double beta decay and limit on the mass of sterile neutrinos.

    hep-phPhys.Part.Nucl.Lett.(2025)·2 citations
15. 15*

    Exploring $T_{{\rm Y}{\rm Y}}$ tetraquark candidates in a coupled-channels formalism

    P.G. Ortega🇪🇸 · D.R. Entem🇪🇸 · F. Fernandez🇪🇸 · J. Segovia🇪🇸

    We investigate the spectrum of $T_{{\rm Y}{\rm Y}}$ tetraquark candidates within a coupled-channels framework. The analysis includes all $L\le 2$ combinations of ${\rm Y}(1S)$, ${\rm Y}(2S)$, ${\eta }_b(1S)$, and ${\eta }_b(2S)$ in the $J^P=0^{\pm },1^{\pm },2^{\pm }$ sectors. The meson-meson interaction is derived from an underlying constituent quark model through the resonating group method, and the properties of the states are obtained from poles of the scattering matrix. We find a rich spectrum of resonant, and virtual, states distributed between the ${\eta }_b(1S){\eta }_b(1S)$ and ${\rm Y}(2S){\rm Y}(2S)$ thresholds. The pattern of poles exhibits approximate heavy-quark spin symmetry multiplets. Several states are dominated by a single channel and can be associated with threshold-driven structures, while higher-mass resonances show sizable mixing among channels involving radially excited bottomonia. The predicted widths range from tens to several hundred MeV. Branching ratios indicate that many states couple predominantly to final states with at least one excited bottomonium, whereas only a subset of the spectrum is expected to be visible in the ${\eta }_b(1S){\eta }_b(1S)$, ${\eta }_b(1S){\rm Y}(1S)$ and ${\rm Y}(1S){\rm Y}(1S)$ channels. These results provide quantitative guidance for experimental searches of fully heavy tetraquarks and offer a test of coupled-channel dynamics and heavy-quark spin symmetry in the $bb\bar{b}\bar{b}$ sector.

    hep-phhep-exhep-latnucl-ex+1PRD(2026)·0 citations
16. 16*

    Renormalization and Factorization Scale-Invariant Predictions for the Higgs Rare Decay $H\to J/\psi +\gamma$ via the Principle of Maximum Conformality

    Qi-Sha Ran🇨🇳 · Xing-Gang Wu🇨🇳 · Jiang Yan🇨🇳 · Xu-Chang Zheng🇨🇳 · Chang-Xin Liu🇨🇳

    We investigate the \(J/\psi\) direct production mechanism in the rare exclusive Higgs decay \(H\to J/\psi+\gamma\) within nonrelativistic QCD (NRQCD), which provides a clean probe for extracting the charm-quark Yukawa coupling to the Higgs boson. The Principle of Maximum Conformality (PMC) is used to remove conventional renormalization-scheme and scale ambiguities in the next-to-next-to-leading-order (N\(^2\)LO) perturbative QCD series. Large logarithmic contributions arising from Yukawa coupling renormalization are resummed, providing a reliable foundation for subsequent analyses. Using the experimentally measured leptonic decay width of \(J/\psi\) and the N\(^2\)LO perturbative result, we extract the factorization-scale-dependent long-distance matrix element \(\langle J/\psi({\bm \epsilon})|\psi^{\dagger}{\bm \sigma}\cdot{\bm \epsilon}\chi(\mu_\Lambda) |0\rangle\). Combining this with the factorization-scale-dependent short-distance coefficient, we obtain a factorization-scale-invariant decay width for the channel. Compared with earlier predictions in the literature, our fixed-order result for \(\Gamma(H\to J/\psi+\gamma)\) is more robust and precise, with good convergence and no renormalization- or factorization-scale dependence. We find \(\Gamma(H\to J/\psi+\gamma) = (6.4574^{+0.3995}_{-0.3995}) \times 10^{-11}\) GeV, where the uncertainty is the quadratic sum of contributions from \(\Delta\alpha_s(m_Z) = \pm 0.0009\), \(\Delta\Gamma_{J/\psi\to e^+e^-} = \pm 0.10\ \text{GeV}\), \(\Delta\overline{m}_c(\overline{m}_c) = \pm 0.0046\ \text{GeV}\), and the estimated magnitude of N\(^3\)LO contributions from Bayesian analysis. This work demonstrates for the first time how the PMC can be applied to obtain fixed-order perturbative predictions that are invariant under both renormalization and factorization scale variations.

    hep-ph1 citation
17. 17*

    Evaluation of Feynman integrals via numerical integration of differential equations

    Pau Petit Rosàs🇬🇧

    We revisit the idea of numerically integrating the differential form of Feynman integrals. With a novel approach for the treatment of branch cuts, we develop an integrator capable of evaluating a basis of master integrals in double and quadruple precision, with significantly smaller run times than other tools. This opens the door to evaluating higher complexity Feynman integrals on the fly in Monte Carlo generators, and enables a cheaper and easy to parallelise generation of grids for the topologies with prohibitive computational times. To show its performance, we test one- and two-loop integral families, achieving evaluation times in double precision of milliseconds and hundreds of milliseconds, respectively. We comment on the results and suggest room for improvement.

    hep-ph1 citation
18. 18*

    Constraints on millicharged particles from thunderstorms on the Solar system planets

    Ekaterina Dmitrieva🇷🇺 · Petr Satunin🇷🇺

    We investigate the production of millicharged particles (mCPs) by the Schwinger mechanism in thunderstorms in the atmospheres of different planets in the Solar system. We consider a thundercloud as a giant capacitor that can be discharged in two ways: either by lightnings or by mCP production. Taking into account the observation of lightning strikes, we establish the constraints on the charge and mass of mCPs. We examine two types of cloud configurations: a simple arrangement of two clouds, and a more complex layered structure that gives rise to potential wells. In the latter case, we take into account the effects of Bose enhancement for scalar mCPs, and Pauli blocking for fermionic ones. We use the observational data of planetary atmospheres obtained by satellite missions to establish constraints on the charge and mass of mCP particles. The best constraints came from the observation of thunderstorms in Saturn's atmosphere under an assumption of layered cloud structure: $q>10^{-24}$ for bosonic mCPs. These constraints for bosons are, to the best of our knowledge, the best in the literature.

    hep-phEPJC(2026)·2 citations
19. 19*

    Lepton mixing and charged lepton flavour violation from inverse seesaw with non-degenerate heavy states

    F. P. Di Meglio🇪🇸 · C. Hagedorn🇪🇸

    We analyse an inverse seesaw scenario with 3+3 gauge singlets. The flavour structure is determined by a flavour symmetry, Delta (3 n^2) or Delta (6 n^2), n integer, and CP and their residual groups among charged leptons and the neutral states. For the latter, the Dirac mass matrix of the gauge singlets carries all non-trivial flavour structure. Consequently, the heavy sterile states form three pseudo-Dirac pairs which have in general distinct masses. We discuss the signal strength of different charged lepton flavour violating processes. Ensuring that the lepton mixing angles can be accommodated at the 3 sigma level or better, we find that the current bounds on the branching ratios of mu -> e gamma, mu -> 3 e, tau -> l gamma and tau -> 3 l, l=e, mu, as well as the rate of mu-e conversion in nuclei do not strongly constrain the considered parameter space, while the limits expected from the upcoming experiments Mu3E, COMET and Mu2e will have a relevant impact.

    hep-ph1 citation
20. 20*

    Connecting Flavor and Baryon Asymmetry via Leptogenesis in Effective Froggatt-Nielsen Theory

    Cheshta Batra🇮🇳 · Rusa Mandal🇮🇳 · Kunal Rawat🇮🇳 · Tom Tong🇮🇳

    We investigate the hierarchical flavor structure of the Standard Model (SM) in a Froggatt-Nielsen (FN) framework, where the spontaneous breaking of a $U(1{)}_{\mathrm{FN}}$ symmetry by a complex flavon field generates fermion masses and mixing patterns through higher-dimensional operators. Extending the setup with three right-handed neutrinos (RHNs), light neutrino masses arise via the Type-I seesaw mechanism. Allowing complex FN coefficients enables a consistent description of the CKM and PMNS matrices while inducing CP-violating signatures in meson decays. Building on our previous work, where the lightest RHN acts as a viable dark matter (DM) candidate produced through freeze-in or freeze-out mechanisms, we investigate the origin of the baryon asymmetry of the Universe. The heavier RHNs generate a lepton asymmetry through out-of-equilibrium decays and scatterings, including both SM channels and additional flavon-induced processes in which the flavon appears as an initial-state particle. We compute the corresponding one-loop CP asymmetries and incorporate these effects in the Boltzmann equations. We show that although freeze-in and freeze-out DM production occur in two qualitatively distinct regions of the FN symmetry-breaking scale $v_{\varphi }$, successful thermal leptogenesis can be achieved in both regimes. In the large-$v_{\varphi }$ (freeze-in-compatible) region, the results approach the standard leptogenesis limit, while in the freeze-out-compatible region the lower value of $v_{\varphi }$ implies lighter RHNs, requiring resonant enhancement. This tightly constrained framework, in which $v_{\varphi }$ simultaneously controls RHN masses and the interaction strengths of the flavon and DM sectors, provides a predictive and unified description of flavor hierarchies, neutrino masses, CP violation, DM, and baryogenesis within a single effective theory.

    hep-phhep-ex1 citation
21. 21*

    Accelerating Feynman Integral Evaluation by Avoiding Contour Deformation

    Stephen P. Jones🇬🇧 · Anton Olsson🇬🇧 · Thomas Stone🇬🇧

    We describe our method for rewriting dimensionally regulated Feynman parameter integrals in the Minkowski regime as a sum of real, positive integrands multiplied by complex prefactors. This representation eliminates the need for a contour deformation, which is one of the main computational bottlenecks in numerical integration. We demonstrate clearly how the method works on two examples, and benchmark the performance against contour deformation as implemented in pySecDec, where we observe performance gains of up to several orders of magnitude. We describe an improvement in the resolution procedure using the Generic Cylindrical Algebraic Decomposition algorithm, which generalises our method to any Feynman integral, including those with massive propagators.

    hep-ph0 citations
22. 22*

    $e^{+}{e}^{-}\to ZH$ at NLO EW matched to a QED parton shower

    Lois Flower🇬🇧 · Marek Schönherr🇬🇧

    To prepare for the next generation particle collider, likely to be a high-energy precision-frontier electron-positron machine, theoretical predictions must improve in tandem. One aspect in which it is necessary to build on the progress made at LEP and at low-energy $e^{+}{e}^{-}$ colliders is in the modelling of initial-state QED radiation from leptons. In this paper we combine the MC@NLO parton shower matching method with QED resummation methods such as the electron structure function to obtain an automated, process-independent NLO-matched QED parton shower. The case of an electron-positron collider provides a particular challenge to the method due to the integrable singularity present in the lepton structure function, at variance with QCD PDFs. We develop new methods to allow a standard dipole parton shower to operate in the presence of this singularity. We validate the method by examining its dependence on infrared parameters and by verifying both the NLO-correctness, and the resummation properties, of the MC@NLO prediction. Finally, we present results for the case of Higgs production in association with an on-shell $Z$ boson at two proposed FCC-ee energies, the first such predictions at EW NLO+PS accuracy.

    hep-ph3 citations
23. 23*

    Strongly interacting singlet scalar dark matter during reheating

    Geneviève Bélanger🇫🇷 · Nicolás Bernal🇦🇪 · Alexander Pukhov🇷🇺

    We revisit the singlet scalar dark matter model in the presence of a non-standard cosmological history prior to radiation domination. We focus on the regime in which the relic abundance is set by 4-to-2 self-annihilations while the dark and visible sectors remain in kinetic equilibrium, i.e. the standard strongly interacting massive particle (SIMP) framework. In the conventional radiation-dominated cosmology, this realization is not viable, as it requires sub-MeV masses and large quartic couplings in tension with bounds on dark matter self-interactions. We show that this conclusion is significantly modified if freeze-out occurs during non-standard cosmological eras. The altered Hubble expansion rate and the possible non-conservation of the standard model entropy change the freeze-out dynamics, allowing the observed relic density to be achieved with perturbative couplings and consistent with astrophysical constraints. We determine the region where SIMP production dominates over the WIMP mechanism and confront the viable parameter space with current and future direct detection and collider bounds.

    hep-ph3 citations
24. 24*

    Beyond21: A Global Framework for Cosmic Dawn and Reionization Within and Beyond the Standard Model

    Omer Zvi Katz🇮🇱

    Observations of the Cosmic Dawn (CD) and Epoch of Reionization (EoR) are steadily improving, opening new opportunities to study early galaxies through complementary probes. To enable consistent interpretation of these observations, we present Beyond21, a fully open-source Python package that implements flexible prescriptions for Pop II and Pop III star formation and computes the resulting radiation backgrounds and their impact on the intergalactic medium. From this coupled evolution, Beyond21 predicts the global 21-cm signal, UV luminosity functions (UVLFs), the ionization history, and the contribution to the observed cosmic X-ray background (CXB) within a single, self-consistent pipeline. A full global evolution run executes in $\sim 0.1\mathrm{s}$ on a single CPU core, enabling broad, high-resolution parameter exploration. The modular architecture facilitates straightforward modification of astrophysical prescriptions and the incorporation of new physics. As an illustrative example, we implement a scenario in which a small fraction of dark matter is millicharged, leading to baryon cooling through elastic interactions.

    ↳ astro-ph.COastro-ph.GAhep-ph0 citations
25. 25*

    STOchastic LAttice Simulation of hybrid inflation

    Tomoaki Murata🇯🇵 · Yuichiro Tada🇯🇵

    We investigate the spatial profile of the curvature perturbation generated in multi-waterfall hybrid inflation models, which are known to produce various topological defects. Using the lattice simulation code STOchastic LAttice Simulation, based on the stochastic formalism of inflation, we analyse six cases by varying the number of waterfall fields $n$ and the functional form of the inflaton potential (``Quadratic'' and ``Cubic'' cases). Our statistical analysis shows that the probability density functions (PDFs) and power spectra are broadly consistent with the so-called stochastic-$\delta N$ algorithm. The ``Cubic'' case also exhibits a characteristic upper bound in the PDF, as discovered in our previous work, that suppresses \acl{PBH} formation while potentially affecting halo formation. Furthermore, we employ the Euler characteristic as a topological diagnostic tool to identify the structures of the waterfall fields as well as the curvature perturbation. We find that the topological defects, such as domain walls ($n=1$), cosmic strings ($n=2$), and monopoles ($n=3$), are reconnected during inflation into finer structures by the stochastic noise, making their correlation lengths much smaller than the Hubble scale at the critical point of the waterfall phase transition counterintuitively. The Euler characteristic also implies global structures of the curvature perturbation for $n=1$, though we do not conclude if they are due to the domain wall, because neither the strings ($n=2$) nor monopoles ($n=3$) leave such structures. The global structures of the curvature perturbation will provide a novel probe for the physics of the early universe.

    ↳ astro-ph.COgr-qchep-phhep-th8 citations
26. 26*

    Dyonic hairy black holes in $U(1)$ gauge-invariant scalar-vector-tensor theories: Cubic and quartic interactions

    Masaki Kitagawa🇯🇵 · Naoki Tsukamoto🇯🇵 · Ryotaro Kase🇯🇵

    We construct and classify asymptotically flat, static, spherically symmetric hairy black hole solutions in $U(1)$ gauge-invariant scalar-vector-tensor (SVT) theories carrying both electric and magnetic charges. Extending previous studies beyond the quadratic sector, we systematically incorporate cubic and quartic interaction terms in the presence of the magnetic charge. We derive a consistency condition for the quartic interaction that eliminates higher-order derivative terms induced by the magnetic charge, ensuring the theory remains second-order. We classify the obtained solutions based on their symmetry properties: shift-symmetric couplings yield secondary hair governed by the Noether current, whereas $\varphi$-dependent interactions generate primary hair. Crucially, our analysis reveals that the magnetic charge plays a key role in activating specific interaction sectors such as the cubic coupling ${\tilde{f}}_3$, which does not appear in the field equations in purely electric configurations. We identify solution branches that are intrinsic to the magnetic charge, as they cease to exist in the vanishing monopole limit ($P\to 0$). Furthermore, we demonstrate that the scalar hair exhibits distinct asymptotic decay rates depending on the interaction type, suggesting possible variations in observational signatures. Finally, we verify the global regularity of these solutions by connecting analytic expansions with numerical integration.

    ↳ gr-qchep-phhep-th0 citations
27. 27*

    On curvature corrections for field theory cosmic strings

    Josu C. Aurrekoetxea🇺🇸 · Jose J. Blanco-Pillado🇪🇸 · Alberto García Martín-Caro🇪🇸 · J.M. Queiruga🇪🇸

    We present a combined analytical and numerical study of the effective action of field theory cosmic strings in the Abelian-Higgs model in flat space. Starting directly from the underlying solitonic field theory description, we provide a systematic derivation of the low energy effective action and present evidence for the absence of nontrivial curvature correction terms when only the translational Goldstone modes are retained. Using this framework, we extend the effective theory to include higher energy fluctuations of the soliton profile, which map to massive degrees of freedom propagating on the worldsheet. We show that the leading curvature contribution enters only through the coupling between these massive modes and the worldsheet Ricci scalar. We validate the resulting effective theory via lattice simulations of the full field theory equations of motion in flat space, implemented with Adaptive Mesh Refinement to capture the string dynamics across different scales. The numerical simulations confirm the dynamics obtained using the effective action in its validity range. Furthermore, they also demonstrate the existence of the predicted parametric instability of excited strings that drives the transfer of energy from massive excitations to the Goldstone sector.

    ↳ hep-thastro-ph.COhep-ph4 citations
28. 28*

    Air shower development through the time dependence of its induced electric field

    Beatriz de Errico🇧🇷 · Charles Timmermans🇳🇱

    Ultra-high energy cosmic rays impinge on the atmosphere and induce air shower cascades, in which huge numbers of particles are produced. By travelling through the Earth's atmosphere and magnetic field, these particles create a noticeable effect on the electric field at the surface. In this article, we demonstrate that parameters of the shower longitudinal development and primary mass can be inferred from mapping the time dependence of the observed electric field to the emitted electric field as a function of slant depth along the shower axis.

    ↳ hep-exhep-ph1 citation
29. 29*

    A likelihood analysis for gamma-ray background models

    Chance Hoskinson🇺🇸 · Jason Kumar🇺🇸 · Pearl Sandick🇺🇸

    Indirect searches for dark matter using dwarf spheroidal galaxies are limited by systematic uncertainties in modeling diffuse gamma-ray backgrounds. We present a likelihood-based comparison of locally constructed empirical background models and theoretically-motivated models that incorporate the Fermi-LAT diffuse background. The empirical models we study include both an independent-binning approach and a covariance-based approach that captures cross-energy correlations. Using ensembles of blank-sky regions and information criteria which account for model complexity, we find that empirical background descriptions provide a statistically competitive fit to gamma-ray data on degree scales in high-latitude regions.

    ↳ astro-ph.HEhep-ph0 citations
30. 30*

    Cost-efficient Bayesian emulation of quark-gluon plasma modeling with variable statistical precision

    R. Ehlers🇺🇸 · Y. Ji🇺🇸 · P. M. Jacobs🇺🇸 · S. Mak🇺🇸

    We present VarP-GP, a new cost-efficient Bayesian emulator for expensive computational models with variable statistical precision. We focus on the interpretation of measurements of the quark-gluon plasma (QGP) generated in high-energy nuclear collisions, through comparison to numerical models using Bayesian Inference. Such inference calculations are computationally expensive and require surrogate model emulation, which is commonly implemented using Machine Learning (ML) based Gaussian processes (GPs). Emulator training data are generated by Monte Carlo simulations whose numerical precision depends on the computational resources utilized; improved precision entails greater computational cost. This study utilizes JETSCAPE simulations of inclusive hadron and jet measurements in nuclear collisions at RHIC and the LHC. The VarP-GP emulator combines information from multiple simulation runs with varying precision across the model parameter space, taking advantage of the smoothness in that space of QCD-driven processes. Comparison to a traditional emulator approach shows a marked reduction in emulator uncertainty at fixed computational cost, indicating that knowledge of the overall contours of the parameter design space is more important for precise emulation than detailed information at a more limited number of design points. As an initial application of VarP-GP, a computationally-expensive model parameter sensitivity study of jet quenching data is reported. The VarP-GP emulator enables new multi-model and many-observable calibrations of QGP data and modeling, which would otherwise not be possible with achievable computing resources.

    ↳ nucl-thhep-phnucl-exPRC(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.