Tue·Apr 7, 2026Tuesday·April 7, 2026

1. 01*

   Global Electroweak Fit Constraints on the Two-Higgs-Doublet Model in Light of the CDF W -Boson Mass

   Hindi Zouhair🇲🇦

   The recent measurement of the $W$ boson mass by the CDF II collaboration exhibits a significant tension with the Standard Model (SM) prediction and other experimental determinations. In this work, we investigate the implications of this result within the framework of the Two-Higgs-Doublet Model (2HDM), focusing on radiative corrections to electroweak precision observables parameterized in terms of the oblique parameters $\Delta S$, $\Delta T$, and $\Delta U$. Using global electroweak fits, we analyze how the inclusion of the CDF measurement modifies the preferred parameter space. We show that the observed shift in $m_W$ can be accommodated in the 2HDM through enhanced contributions to $\Delta T$, arising from mass splittings in the scalar sector. The resulting constraints on the scalar spectrum are presented and compared with those obtained using previous electroweak data. These results highlight the role of precision observables in probing extended Higgs sectors and provide updated bounds on viable 2HDM parameter space.

   hep-ph0 citations
2. 02*

   Monte Carlo Event Generation with Continuous Normalizing Flows

   Enrico Bothmann🇨🇭 · Timo Janßen🇩🇪 · Max Knobbe🇺🇸 · Bernhard Schmitzer🇩🇪 · Fabian Sinz🇩🇪

   We apply Continuous Normalizing Flows trained with the Flow Matching method to the problem of phase-space sampling in Monte Carlo event generation for high-energy collider physics. Focusing on lepton-pair and top quark pair production with multiple jets, the two computationally most expensive processes at the Large Hadron Collider, we train helicity-conditioned Continuous Normalizing Flows to remap the random numbers used in matrix element evaluation. Compared to standard methods, we achieve unweighting efficiency improvements by factors of up to 184 and 25 for the two processes at their respective highest jet number, at the cost of an increased evaluation time. When combining the advantages of Continuous Normalizing Flows with the fast evaluation times of Coupling Layer based Flows, using the RegFlow approach, we find parton-level unweighted event generation walltime gains of about a factor of ten at the highest jet numbers. These substantial gains highlight the promise of samplers based on machine learning for next-generation collider experiments.

   hep-phPRL(2026)·9 citations
3. 03*

   Multiplicity dependence of thermal parameters in pp collisions at $\sqrt{s}=7$ TeV from statistical hadronization fits

   R. C. Baral🇮🇳

   We perform a systematic thermal analysis of identified hadron yields measured by the ALICE Collaboration in proton-proton collisions at $\sqrt{s}=7$ TeV across charged-particle multiplicity classes within the statistical hadronization model using the Thermal-FIST framework. Global fits are used to extract the chemical freeze-out temperature $T$, system volume $V$, and strangeness saturation parameter ${\gamma }_S$. The extracted temperature remains approximately constant at $T\simeq 155$-$165$ MeV across multiplicity, while the effective volume exhibits an approximately linear increase with event activity. In contrast, ${\gamma }_S$ shows a clear rise with multiplicity, indicating a progressive reduction of strangeness suppression. Derived thermodynamic quantities obtained within the model show that the energy density increases with multiplicity, while the average energy per particle increases from $\sim 0.85$ GeV to $\sim 0.99$ GeV, remaining close to $1$ GeV. Particle-to-pion ratios reproduce the strangeness-dependent hierarchy observed by ALICE. A systematic comparison of fits constrained by hidden- and open-strangeness hadrons reveals a persistent offset in ${\gamma }_S$, corresponding to an approximately $4\sigma$ separation between the $\varphi$- and $\Omega$-constrained results within the present quadrature-summed uncertainty treatment. These results indicate that, although high-multiplicity proton-proton collisions exhibit several features compatible with an approximate thermal description, a single global freeze-out parameterization does not fully capture the strange sector.

   hep-ph1 citation
4. 04*

   Gravitational transverse momentum distribution of proton

   Kauship Saha🇮🇳 · Dipankar Chakrabarti🇮🇳 · Asmita Mukherjee🇮🇳

   We present the first study of quark gravitational transverse-momentum distributions within the light-front quark--diquark model (LFQDM) inspired by the soft-wall AdS/QCD framework. We derive analytical expressions for the six unpolarized (T-even) gravitational transverse-momentum-dependent distributions (gravitational--TMDs) for up and down quarks within the model and compute the corresponding gravitational parton distribution functions (gravitational--PDFs). We further verify that these unpolarized gravitational--TMDs satisfy the model-independent relations with quark TMDs. In addition, we explore the connection of gravitational TMDs with the transverse isotropic pressure and shear-force distributions in momentum space, as well as with the average longitudinal momentum carried by up and down quarks within the model.

   hep-ph1 citation
5. 05*

   Two Lectures on the Phase Diagram of QCD

   Larry McLerran🇺🇸

   The phase diagram of QCD at finite temperature and density is discussed. Large numbers of quark colors, $N_{\mathrm{c}}>>1$, is used to explain generic features of the phase diagram. For temperatures below $T\le 160$~MeV at zero baryon number density, the three dimensional string model is shown to describe the thermodynamics of QCD, and as well, the integrated spectrum of non-Goldstone mesons and glueballs. The lowest mass state in the spectrum of the open and closed string is treated separately due to the tachyon problem of string theory. This is with no undetermined free parameters. It is argued that there are at least three phases at zero baryon number density characterized by the $N_{\mathrm{c}}$ dependence of extensive thermodynamic quantities. It is also argued that the intermediate phase has restored chiral symmetry. At high baryon number density and low temperature, again there are three phases. A Quarkyonic phase, with energy density of order $N_{\mathrm{c}}$, is distinguished from its counterpart at low baryon density and temperature by its chiral properties.

   hep-phhep-thnucl-thActa Phys.Polon.B(2026)·3 citations
6. 06*

   What spectators do during inflation

   Daniel Boyanovsky🇺🇸

   The inflaton equation of motion including one loop radiative corrections from spectator fields is obtained. We consider a massless scalar conformally coupled to gravity and a massless fermion Yukawa coupled to the inflaton as models for spectators that \emph{do not feature} gravitational particle production, their production during slow roll is solely a consequence of their coupling to the inflaton. The one-loop self energy and the fully renormalized equation of motion of the inflaton are obtained and solved explicitly for an inflaton potential $m^2{\phi }^2/2$. The solution features Sudakov-type logarithmic secular terms, which are resumed via the dynamical renormalization group and compared to the solutions with a phenomenological friction term. During $N_e$ e-folds of slow roll inflation the inflaton evolves as ${\phi }_{Isr}^{(0)}(t)e^{\frac{m^2\Gamma }{9H^3}{N}_e(t)}$ for the phenomenological friction term $\Gamma$ and ${\phi }_{Isr}^{(0)}(t)e^{{\rm Y}{N}_e^2}$ with ${\rm Y}=-\frac{{\lambda }^2}{24{\pi }^2{H}^2};\frac{y_R^2}{12{\pi }^2}$ for the radiative corrections from bosonic and fermionic spectators respectively where ${\phi }_{Isr}^{(0)}(t)$ is the slow roll solution in absence of interactions, showing that a phenomenological friction term is not reliable. A generalization of the optical theorem to a finite time domain and cosmological expansion is introduced to obtain the distribution function $f(k,t)$ and total number of spectators produced \emph{during slow roll}. $f(k,t)$ is peaked at superhorizon scales and the total number of particles grows $\propto e^{3N_e}$. A non-perturbative mean field theory is introduced to describe the self-consistent evolution of the inflaton coupled to spectators, its linearized version reproduces the self-energy, the inflaton equation of motion and the results on particle production.

   hep-phastro-ph.COgr-qchep-thClass.Quant.Grav.(2026)·0 citations
7. 07*

   Photon Propagation through Axion Clouds around Magnetized Compact Objects: Time Delays and Polarimetric Signatures

   M. M. Chaichian🇫🇮 · B. A. Couto e Silva🇧🇷 · B. L. Sánchez-Vega🇧🇷

   Temporal offsets between Gamma-Ray Bursts (GRBs) and high-energy neutrinos probe propagation effects in extreme astrophysical environments. We investigate whether such offsets can be generated by photon propagation through dense axion clouds gravitationally bound to strongly magnetized compact objects, such as canonical pulsars. Working within the Euler--Heisenberg effective theory extended by the axion sector, we derive the photon dispersion relations in a strong magnetic background permeated by an oscillating axion field. The magnetized vacuum is birefringent already at the Euler--Heisenberg level and the axion cloud superimposes density-dependent, time-dependent, and parity-odd structure on this baseline. The resulting geometry-dependent deviations from luminal propagation yield kinematic time delays reaching $\Delta t_{\perp }\simeq 9.3\times 10^{-12}$ s for $\mathbf{k}\perp \mathbf{B}$, far too small to account for macroscopic multimessenger offsets, so that propagation through such environments cannot, by itself, rule out Lorentz-invariance violation as an explanation for GRB offsets. In the polarization sector, we show that the axion-induced circular birefringence is an endpoint effect and therefore does not produce a leading net rotation for a complete vacuum-to-vacuum transit through a localized cloud. For configurations with a nonzero axion-field endpoint contrast, the same parity-odd phase defines a conditional environmental sensitivity benchmark. We find that this mechanism is optimally sensitive in the ultralight regime, yielding a benchmark reach of $g_{a\gamma \gamma }\lesssim 2.5\times 10^{-10}{\mathrm{GeV}}^{-1}$ for canonical pulsar fields and axion masses near $m_a\sim 10^{-9}$ eV, and we identify the parity-odd (chiral) birefringence induced by the oscillating cloud as the signature that distinguishes the axion contribution from the calculable QED baseline.

   hep-phastro-ph.HEhep-th0 citations
8. 08*

   Geometric Baryogenesis with Chiral-Time Equivalence

   Sameer Ahmad Mir🇨🇦 · Arshid Shabir🇨🇦 · Swatantra Kumar Tiwari🇮🇳 · Mir Faizal🇨🇦

   The asymmetry between matter and antimatter demands a cause as simple as it is profound. Here we show that a single geometric principle Chiral-Time Equivalence (CTE)-suffices to generate and correlate the required CP violation with the time orientation of the cosmos. Promoting the Immirzi parameter to a pseudoscalar Nambu-Goldstone field $\Phi$, CTE fixes the leading operators: a shift-symmetric derivative portal $(({\partial }_{\mu }\Phi )J_{B-L}^{\mu }/M_{\ast })$ that acts as a dynamical chemical potential in FRW, and a topological term $(\Phi R\tilde{R})$ that imprints parity on tensor modes. In thermal equilibrium this structure produces gravity-assisted leptogenesis, whose magnitude is set at the decoupling temperature by susceptibilities rather than by tuned departures from equilibrium. A fully flavored Boltzmann network with curvature sources captures flavor transfer and washout, while slow-roll and resonant regimes are established via thermodynamic and Kubo formulas. Consistency is secured by an EFT analysis (stability, perturbative unitarity, and BBN safety), and by explicit elimination of EC torsion and control of dCS birefringence in the small-coupling domain. The most striking prediction is a sign locking among ${\eta }_B$, tensor chirality ${\chi }_T$, and the drift of $\Phi$, together with a tri-observable relation that ties ${\eta }_B$ to cosmic birefringence $\Delta \alpha$ and ${\chi }_T$. Thus a single, symmetry-protected geometric origin renders the baryon excess testable by TB/EB correlations and stochastic-wave chirality, and calculable within a minimal, ultraviolet-anchored effective theory.

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

   Reality-constrained Minimal Yukawa Structure in SO(10) GUT

   Shaikh Saad🇸🇮 · Vasja Susič🇮🇹

   We investigate the minimal Yukawa sector of grand unified theories based on $\mathrm{SO}(10)$ symmetry, consisting of a Higgs structure with representations ${10}_{\mathbb{R}}\oplus {120}_{\mathbb{R}}\oplus 126$. In this framework, where ${10}_{\mathbb{R}}$ and ${120}_{\mathbb{R}}$ are real scalars, we derive the associated $\mathrm{SO}(10)$ reality conditions for their weak-doublet constituents -- both by explicit computation and an analytic reframing into a Pati-Salam-like description -- to revisit previously reported fermion mass relations. Our analysis revises these earlier results, in particular by introducing a relative sign difference between the reality constraints on the two weak doublets in ${120}_{\mathbb{R}}$, yielding a new parameter (a magnitude) in the fermion mass relations. Our formalism is fully general and provides a systematic framework for deriving Clebsch-Gordan coefficients and implementing reality constraints for arbitrary parent-daughter representation pairs of $\mathrm{SO}(10)$ and its Pati-Salam subgroup. Incorporating these corrections, we perform an extensive numerical scan of the parameter space and find that the model successfully reproduces SM fermion masses and mixings, including recent precision measurements of solar oscillation parameters by JUNO. It accommodates both octants of ${\theta }_{23}$ while mildly disfavoring ${\delta }_{\mathrm{PMNS}}\sim (140^{\circ },220^{\circ })$. The model predicts a strongly hierarchical right-handed neutrino spectrum $(10^5,10^{12},10^{15})$ GeV and a neutrinoless double beta decay parameter $m_{\beta \beta }\sim 3$-$4$ meV, just below future experimental sensitivity. Proton decay is dominated by $p\to {\pi }^{+}\overline{\nu }$ and $p\to {\pi }^0{e}^{+}$, making these channels testable in upcoming experiments.

   hep-ph1 citation
10. 10*

    Associated production of $J/\psi$ mesons and photons in the Parton Reggeization Approach and the double parton scattering model

    Lev Alimov🇷🇺 · Vladimir Saleev🇷🇺

    We study the contribution of double parton scattering (DPS) to the associated production of $J/\psi$ mesons and photons with large transverse momenta in proton-proton collisions. Cross sections are computed within high-energy factorization using the Parton Reggeization Approach (PRA). We used two frameworks for hadronization of the $c\bar{c}$ pair into charmonium: nonrelativistic QCD (NRQCD) and the improved color evaporation model (ICEM). Hadronization model parameters are fixed using single $J/\psi$ production experimental data from the CMS and ATLAS collaborations at the Large Hadron Collider (LHC). We show that the DPS contribution significantly exceeds the single parton scattering (SPS) contribution and that theoretical predictions are strongly sensitive to the choice of hadronization model. We made predictions for various differential cross sections and correlation spectra for the associated $J/\psi$ and photon production at $\sqrt{s}=13$ TeV.

    hep-ph0 citations
11. 11*

    Temperature Effects on a Vector Hidden-Charm Molecule

    E. Güngör🇹🇷 · H. Sundu🇹🇷 · J.Y. Süngü🇹🇷 · E. Veli Veliev🇹🇷

    We investigate the thermal properties of the $Y(4500)$ state within the framework of thermal QCD sum rules, assuming a $D_s{\bar{D}}_{s1}$ molecular configuration with $J^{PC}=1^{--}$. The analysis is performed at both zero and finite temperatures, employing the operator product expansion up to dimension-5 condensates. The Borel window and continuum threshold are carefully selected to ensure OPE convergence and pole dominance. As the temperature approaches the deconfinement temperature $T_c$, the $Y(4500)$ undergoes significant medium modifications: its mass decreases by $29\%$ and its decay constant is suppressed by $94\%$ relative to their vacuum values, while the decay width increases by $35\%$, signaling the dissociation of the state in the medium. These results indicate that the $Y(4500)$ becomes unstable near $T_c\approx 155\mathrm{MeV}$, consistent with its melting into the quark-gluon plasma. The obtained thermal spectral parameters may serve as signatures for identifying the $Y(4500)$ in heavy-ion experiments at RHIC and LHC, and provide predictions for sequential suppression patterns in the exotic hadron sector.

    hep-ph0 citations
12. 12*

    Importance of unitarity in the search for heavy neutrinos in $e^{+}{e}^{-}\to W^{+}{W}^{-}$

    G.A. Chachava🇷🇺 · S.I. Godunov🇷🇺

    We study the process $e^{+}{e}^{-}\to W^{+}{W}^{-}$ with the aim of estimating the prospects for observing heavy neutrinos contributions at future $e^{+}{e}^{-}$-colliders. In this work, we consider two implementations of heavy-light neutrino mixing: a linearized mixing approximation applied in popular models and an exact unitary mixing scheme. We conclude that the approximate realization leads to physically incorrect results for this process, while exact unitary mixing provides some signatures that can be experimentally checked.

    hep-phhep-exPRD(2026)·1 citation
13. 13*

    Dynamical CP Violation from Non-Invertible Selection Rules

    Hiroshi Okada🇨🇳 · Hajime Otsuka🇯🇵

    We propose a novel mechanism in which leptonic CP-violating phases are generated dynamically through the radiative breaking of non-invertible selection rules. In this framework, tree-level mass matrices, initially constrained by a CP-like symmetry within a non-invertible structure, acquire flavor-dependent phases once loop corrections are incorporated. Furthermore, these corrections can also generate mass terms, thereby addressing the mass hierarchy problem. As an illustrative example, we employ the Inverse Seesaw (ISS) model to demonstrate how the Majorana mass of the light sterile neutrino $N_L$ arises via this mechanism while simultaneously realizing CP violation. Although our analysis is carried out within the ISS framework, the mechanism has broader implications, potentially offering new perspectives on CP-related problems such as the strong CP problem, leptogenesis, and baryogenesis. This work thus establishes a foundation for exploring the dynamical breaking of non-invertible selection rules as a novel origin of CP violation in particle physics.

    hep-phJHEP(2026)·3 citations
14. 14*

    Multi-field oscillons/I-balls in the Friedberg-Lee-Sirlin model

    Kai Murai🇯🇵 · Tatsuya Ogawa🇯🇵 · Fuminobu Takahashi🇯🇵

    We study oscillon/I-ball solutions in a real scalar version of the Friedberg-Lee-Sirlin (FLS) model. Using the multiple-scale analysis, we derive the conditions for oscillon solutions and explore multi-field oscillon configurations. In these configurations, the two fields form co-located oscillons that oscillate with frequencies set by their respective masses. These multi-field oscillons can be viewed as a bound state of two oscillons due to attractive interactions between the fields. We confirm these analytical predictions through numerical lattice calculations. This work extends the standard picture of single-field oscillons and may be relevant for cosmological scenarios involving multiple interacting real scalar fields.

    hep-phastro-ph.COhep-thPRD(2026)·0 citations
15. 15*

    Neutron star with dark matter using vector portal

    Deepak Kumar (IISER Berhampur)🇮🇳 · Ranjita K. Mohapatra (Rajdhani College)🇮🇳 · Hiranmaya Mishra (IOP & NISER)🇮🇳 · Sudhanwa Patra (IIT Bhilai & IOP)🇮🇳

    Compact astrophysical objects, such as neutron star, can provide a unique environment where the interplay between strongly interacting nuclear matter and dark matter (DM) can yield possible observable signatures. We investigate here the impact of fermionic DM interacting with nucleons via a vector mediator ($Z^{\prime }$) portal inside neutron stars using the relativistic mean-field (RMF) framework. Unlike scalar portal DM models, which primarily modify the effective nucleon mass through scalar interactions, vector mediators (Z') introduce additional repulsive interactions that directly affect the baryonic chemical potential and the pressure of dense matter. We show that the precise measurements of neutron star properties, including the mass-radius relation and tidal deformability from gravitational wave observations, X-ray and radio observations of pulsars, can shed light on properties of DM. We study the gross structural properties of a neutron star using the Tolman-Oppenheimer-Volkoff (TOV) equations, employing an equation of state (EOS) for neutron star matter in the presence of vector portal-assisted DM. The resulting stellar configurations consistent with observational bounds from gravitational wave observations (GW170817) in LIGO/Virgo and X-ray observations of pulsar PSR J0030+0451 in NICER, are shown to constrain the vector portal DM parameters. It is observed that, while large portal mass can soften the EOS of the DM admixed neutron star matter, the light portal mass can make the EOS stiffer at large densities resulting in distinct mass-radius relation and the tidal deformability between the two scenarios. The vector portal DM scenario, with DM interaction with quarks via Z' vector boson, can establish a direct connection to terrestrial searches, including direct and indirect detection and collider searches for the Z' boson.

    hep-phnucl-thPRD(2026)·2 citations
16. 16*

    Predictions of Modular Symmetry Fixed Points on Neutrino Masses, Mixing, and Leptogenesis

    Priya🇮🇳 · B. C. Chauhan🇮🇳 · Deepak Kumar🇮🇳 · Takaaki Nomura🇨🇳

    In recently proposed framework of non-holomorphic modular symmetry introduces the concept of negative and zero modular weight of Yukawa couplings. These Yukawa couplings are function of complex modulus $\tau$, which is responsible for the CP asymmetry produced during leptogenesis. In this work, we restrict the $\tau$ on the fixed points of modular symmetry rather than its fundamental domain in such manner Yukawa couplings are also get fixed. We have adopt this framework and propose a type III seesaw mechanism. The model is tested against neutrino oscillation data through a ${\chi }^2$ analysis using NuFIT~6.1. To test the stability of these predictions, we also analyze regions near each fixed point by introducing a deviation $\tau \to {\tau }_{\mathrm{fixed}}(1+ϵe^{i\varphi })$ with $ϵ\in (0,0.1)$ and $\varphi \in (-\pi ,\pi )$. Our results show that certain fixed points, along with their nearby regions, are capable of producing viable neutrino phenomenology while also generating the observed baryon asymmetry of the Universe.

    hep-ph5 citations
17. 17*

    Twin hypercharges

    Nguyen Huy Thao🇻🇳 · Nguyen Thi Nguyet Nga · Tran Dinh Tham🇻🇳 · Phung Van Dong🇻🇳

    It is shown that a duplication of the hypercharge, which is identical for the normal sector but different for the dark sector, may manifestly address neutrino mass and dark matter.

    hep-phhep-th0 citations
18. 18*

    Natural SUSY with mixed axion/axino dark matter

    Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Kairui Zhang🇺🇸

    While supersymmetric models provide a solution to the big hierarchy problem, natural SUSY is also allowed by the little hierarchy problem. In supersymmetric models which include the Peccei-Quinn (PQ) solution to the strong CP problem, one expects the presence of an axion-axino-saxion supermultiplet with a micro-eV-scale axion and a saxion with mass of order the soft breaking scale. The axino mass is much more model-dependent, and may occur in the range of keV-TeV: over 9 orders of magnitude. This leads to the possibility of the axino as lightest SUSY particle (LSP) and the presence of mixed axion plus axino dark matter. The case of natural SUSY with higgsino-like WIMPs as LSP seems (nearly) excluded by multi-ton noble liquid WIMP detector limits, even in the case where the LSP has a depleted abundance compared to axions. We examine the case where the axino is LSP leading to mixed axion-axino dark matter in a natural SUSY context. We map out regions of PQ scale f_a vs. axino mass m_{\ta} parameter space where such a scenario remains viable in both the SUSY DFSZ and KSVZ axion models. For axino mass ~100 keV, we find solutions in accord with the measured dark matter abundance with mainly warm axino dark matter for f_a~ 10^{11} GeV and also solutions with mainly axion cold DM and a tiny axino contribution for higher f_a~ 3\times 10^{12} GeV.

    hep-phPLB(2026)·3 citations
19. 19*

    CP-violation effects in neutral meson oscillations in the left-right weak interaction model

    A.P. Serebrov🇷🇺 · O.M. Zherebtsov🇷🇺 · A.K. Fomin🇷🇺 · R.M. Samoilov🇷🇺 · N.S. Budanov🇷🇺

    An analysis of the latest, most accurate experimental data on neutron decay indicates the need to expand the Standard Model by introducing an admixture of the right vector boson $W_R$ with a mixing angle of $\zeta =-0.039\pm 0.014$ with the left vector boson $W_L$ and a ratio of the squares of the masses of $W_1$ and $W_2$ equal to $\delta =0.070\pm 0.010$. In this regard, the possibility of describing CP-violation effects in neutral meson oscillations within the framework of the left-right weak interaction model with parameters $\delta$ and $\zeta$ was investigated. It was shown that within this model, CP violation effects in the decays of $K^0$-mesons, $D^0$-mesons, $B^0$-mesons, and $B_s^0$-mesons can be successfully described. The results of calculations within the extended left-right model with parameters $\delta$ and $\zeta$ are confirmed by experimental results. Thus, the nature of CP violation is related to the presence of a right-handed vector boson admixture.

    hep-phhep-ex0 citations
20. 20*

    Precision QCD with the Electron-Ion Collider

    C. Alexandrou🇨🇾 · M. Arratia🇺🇸 · E.C. Aschenauer🇺🇸 · A. Avkhadiev🇺🇸 · P.V. Balachandran🇺🇸 · V. Bertone🇫🇷 · I. Borsa🇩🇪 · M. Cerutti🇫🇷 · X. Chu🇺🇸 · W. Cosyn🇺🇸 · D. de Florian🇦🇷 · A. Dumitru🇺🇸 and 57 other authors

    This document summarizes the discussions at the program "Precision QCD with the Electron Ion Collider", held from May to June 2025 at the Institute for Nuclear Theory (INT) at the University of Washington. The program was co-sponsored by the INT and by the Center for Frontiers in Nuclear Science (CFNS, Stony Brook University). Over its five-week duration it brought together about 70 theorists, experimentalists and computer scientists all interested in the physics program at the future Electron Ion Collider in preparation at Brookhaven National Laboratory. Key topics at the program were: higher-order perturbative-QCD calculations and techniques; nuclear structure and tomography; comparisons of phenomenological and lattice determinations of parton distribution functions; identification of signature observables for saturated gluons; assessment of the importance of AI techniques for EIC studies and detector development.

    hep-ph12 citations
21. 21*

    Glueballs, Constituent Gluons and Instantons

    Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸

    We present a constituent two-gluon description of the lowest-lying glueball states in pure Yang--Mills theory, calibrated against quenched lattice results. The framework incorporates an instanton-induced dynamical gluon mass, Casimir-scaled adjoint confinement, the short-distance adjoint Coulomb interaction, and instanton-induced central and tensor forces. The scalar $0^{++}$ glueball is found to be exceptionally compact, with a radius of order the instanton size, $\rho \sim \frac{1}{3}\mathrm{fm}$, consistent with lattice indications. By contrast, the tensor $2^{++}$ state remains spatially extended due to the centrifugal barrier. We also discuss the role of $S$-$D$ mixing. A semiclassical analysis further supports Regge behavior for excited states, in agreement with lattice results.

    hep-phhep-lathep-thnucl-th1 citation
22. 22*

    Study of the molecular Properties of the $P_c$ and $P_{cs}$ States

    Jing-Zhi Cao🇨🇳 · Huan-Yu Wei🇨🇳 · Jiao-Xue Yang🇨🇳 · Jian Sun🇨🇳 · Chu-Wen Xiao🇨🇳

    In the present work, we investigate the molecular properties of the hidden charm pentaquark states $P_c$ and $P_{cs}$ with a coupled channel framework that combines heavy quark spin symmetry and the local hidden gauge formalism. By solving the Bethe-Salpeter equation with the cutoff method, we obtain the pole trajectories, wave functions, and root-mean-square radii. For the hidden charm system, the full coupled channel interactions respecting the heavy quark spin symmetry are essential to generate the $P_c$ states, which significantly affect the poles' widths. The dominant bound channels are $\bar{D}{\Sigma }_c$ and ${\bar{D}}^{\ast }{\Sigma }_c$, which couple strongly to the lower decay channels. In contrast, for the hidden charm strange system, the full heavy quark spin symmetry treatment is not necessary, where the splitting PB and VB sectors yield similar results. The main bound channels $\bar{D}{\Xi }_c$ and ${\bar{D}}^{\ast }{\Xi }_c$ couple strongly to ${\bar{D}}_s{\Lambda }_c$ and ${\bar{D}}_s^{\ast }{\Lambda }_c$, respectively, but weakly to the lower decay channels, different from the hidden charm case. The trajectories of the pole widths for the loosely bound channels $\bar{D}{\Xi }_c^{\prime }$, ${\bar{D}}^{\ast }{\Xi }_c^{\prime }$, and ${\bar{D}}^{\ast }{\Xi }_c^{\ast }$ exhibit distinct behaviors. Notably, all the primary bound channels have similar binding energies in the single channel interactions due to equally attractive potentials. Furthermore, we also calculate the wave functions and root-mean-square radii of the corresponding poles. The wave functions are localized within $0\sim 6$ fm and vanish fast beyond $4$ fm. The root-mean-square radii, evaluated by two consistent methods, typically lie between $0.5$ and $2$ fm, comparable to the characteristic scale of molecular states. The root-mean-square radii depend on the pole trajectories and differ among the full coupled channel case, the split PB and VB sectors, and the single channel interactions.

    hep-phPRD(2026)·0 citations
23. 23*

    ${\mathbf{B}}_{\mathbf{c}}$ Meson Spectroscopy from Bayesian MCMC: Probing Confinement and State Mixing

    Christas Mony A.🇮🇳 · Rohit Dhir🇮🇳

    We present a Bayesian study of the $B_c$ meson spectrum using three non-relativistic confining potentials, namely the Cornell potential, a logarithmically modified extension, and a screened Cornell form. Parameters for each potential are sampled using Markov chain Monte Carlo (MCMC), retaining correlations among the fitted parameters. The resulting parameter distributions are used to calculate the $B_c$ spectrum through the $6D$ multiplet, including masses, spin-dependent splittings, mixing angles, and wave-function observables. The predicted masses are further examined through Regge trajectories. The low-lying spectrum is relatively stable across the three potentials, while their predictions become increasingly separated with excitation as the states probe larger distances, accompanied by growing parameter-induced uncertainties. The Regge trajectories show stronger non-linearity for low-lying states and progressively approach linear behavior with excitation. These results quantify the sensitivity of the predicted excited $B_c$ spectrum to the chosen confining interaction and provide uncertainty estimates for states that remain experimentally less explored.

    hep-phhep-ex1 citation
24. 24*

    Probing Unification Scenarios with Big Bang Nucleosynthesis

    I. M. Dreyer🇵🇹 · C. J. A. P. Martins🇵🇹

    We extend a recently developed Big Bang Nucleosynthesis (BBN) code, {\tt PRyMordial}, to constrain a broad class of Grand Unified Theories to which BBN is sensitive, since these lead to varying fundamental couplings. A previously developed self-consistent perturbative analysis of the effects of these variations has been implemented in {\tt PRyMordial}, leading to robust constraints of the value of the fine-structure constant, $\alpha$, at the BBN epoch using current observations of Helium-4 and Deuterium abundances. We explored two different viable scenarios, relying on alternative assumptions on the gravitational sector: the variation of the gravitational coupling can be implemented by varying either particle masses, or Newton's gravitational constant. For the variation of masses, we obtained at $68\%$ confidence level a constraint on the relative variation of $\alpha$, between the BBN epoch and the present-day laboratory value, of $\Delta \alpha /\alpha =2\pm 51$ ppm (parts per million), while for the variation of Newton's constant the analogous constraint is $\Delta \alpha /\alpha =2\pm 22$ ppm. We also show that, given these constraints, these models do not provide a solution to the cosmological Lithium problem.

    hep-phastro-ph.COPRD(2026)·0 citations
25. 25*

    Light neutrinos, Dark matter and leptogenesis near electroweak scale and $Z_4$ symmetry

    Kunal Pandey🇮🇳 · Rathin Adhikari🇮🇳

    Considering $Z_4$ symmetry in Type I seesaw scenario, one could obtain mass-squared differences of light neutrinos, mixings and $CP$ violating phase within $3\sigma$ confidence level based on neutrino oscillation data. This is possible with only three independent complex parameters for allowed Yukawa couplings and one real mass parameter for heavy right handed neutrino fields around electroweak scale. After considering only three more real parameters as coming from small soft-symmetry breaking terms, the lightest right handed neutrino could be considered as dark matter candidate via freeze-in mechanism and the other two heavier right handed neutrinos through their decays, could generate the baryonic asymmetry of the universe naturally via resonant leptogenesis.

    hep-phastro-ph.HEhep-th0 citations
26. 26*

    Unquenched Radially Excited $P$-wave Charmonia

    George Rupp🇵🇹

    The ground-state positive-parity charmonia ${\chi }_{c0}(1P)$, ${\chi }_{c1}(1P)$, $h_c(1P)$, and ${\chi }_{c2}(1P)$ are generally well described in static (``quenched'') quark models, in which dynamical effects of actual or virtual strong decay are neglected. In contrast, the five PDG candidates for $P$-wave charmonia in the energy region 3.85-3.95 GeV, probably including the first radial excitations of the above ones, display a totally different and quite disparate mass pattern. Moreover, two scalar states are listed, viz. ${\chi }_{c0}(3860)$ and ${\chi }_{c0}(3915)$, the former one apparently being very broad. Preliminary results will be presented here for the first radial excitations of the lowest $P$-wave $c\bar{c}$ states, obtained with the Resonance-Spectrum Expansion while including in the calculation all OZI-allowed decay channels of the most relevant charm-meson pairs. Employing a generalised scheme of computing coupling constants for decays based on the ${}^3{P}_0$ model ensures that no distortion of the spectra will occur due to the different classes of allowed decay channels for the various positive-parity charmonia.

    hep-phhep-exActa Phys.Polon.Supp.(2026)·0 citations
27. 27*

    Electroweak Doublet Dark Matter for a Galactic Halo Gamma-Ray Excess

    Yasunori Nomura🇺🇸 · Tomonori Totani🇯🇵

    Weakly interacting massive particles provide a well-motivated framework for dark matter, naturally reproducing the observed relic abundance through thermal freeze-out. A recent claim of an indirect-detection signal from the Galactic halo, consistent with dark matter annihilation in the mass range 400--800 GeV, motivates a reexamination of minimal models that can account for such a signal while remaining consistent with existing constraints. In this paper, we analyze the simplest extensions of the Standard Model capable of explaining the signal. We show that electroweak doublet dark matter with Higgs-portal interactions provides a natural and economical explanation. The model predicts annihilation predominantly into gauge bosons with characteristic branching fractions and allows for inelastic dark matter with a mass splitting of order 100 keV, intriguingly consistent with a recent direct-detection anomaly. Possible enhancements of the present-day annihilation rate relative to the thermal value are also discussed, including a simple extension with a light scalar field that induces Sommerfeld enhancement.

    hep-phastro-ph.CO5 citations
28. 28*

    Signals of Doomsday III: Cosmological signatures of the late time $U(1{)}_{EM}$ symmetry breaking

    Amartya Sengupta🇺🇸 · Dejan Stojkovic🇺🇸

    Of the universe's original gauge symmetries, only $SU(3{)}_c$ (quantum chromodynamics) and $U(1{)}_{\mathrm{EM}}$ (electromagnetism) remain unbroken today. There is, however, no reason to assume that these symmetries are permanent. This paper explores the potential astrophysical observational signatures of a late-time breaking of $U(1{)}_{\mathrm{EM}}$. We present a model with a new massive scalar field whose potential supports a first-order phase transition through the nucleation of true-vacuum bubbles. If the propagation of the bubble walls slows down due to interactions with the surrounding matter and radiation, these signals can reach us before the bubble wall itself arrives. Using the vacuum-mismatch method, we calculate the spectrum of particles produced by such a bubble until the terminal velocity is reached. In addition, we show that frictional dissipation at terminal wall velocity generates a large population of thermally produced scalars and massive photons, which continues even after the mismatch channel shuts off. We then use event generators to simulate the decays of the new scalar and the massive photon into Standard Model particles and obtain, as the final result, the energy spectra of photons and neutrinos. Since the dominant final decay products after hadronization and the decay of unstable particles are photons and neutrinos, they act as long-range signatures of the transition. We also estimate the possible lead time of these photon and neutrino signals relative to the arrival of the bubble wall itself, showing that even a modest subluminal wall velocity can in principle provide an observable precursor. For the conservative set of parameters used here, the thermal channel produces a macroscopically large burst of high-energy photons and neutrinos, which could in principle be detectable from sufficiently nearby bubbles with present or future multi-messenger facilities.

    hep-ph0 citations
29. 29*

    Learning to Unscramble Feynman Loop Integrals with SAILIR

    David Shih🇺🇸

    Integration-by-parts (IBP) reduction of Feynman integrals to master integrals is a key computational bottleneck in precision calculations in high-energy physics. Traditional approaches based on the Laporta algorithm require solving large systems of equations, leading to memory consumption that grows rapidly with integral complexity. We present SAILIR (Self-supervised AI for Loop Integral Reduction), a new machine learning approach in which a transformer-based classifier guides the reduction of integrals one step at a time in a fully online fashion. The classifier is trained in an entirely self-supervised manner on synthetic data generated by a scramble/unscramble procedure: known reduction identities are applied in reverse to build expressions of increasing complexity, and the classifier learns to undo these steps. When combined with beam search and a highly parallelized, asynchronous, single-episode reduction strategy, SAILIR can reduce integrals of arbitrarily high weight with bounded memory. We benchmark SAILIR on the two-loop triangle-box topology, comparing against the state-of-the-art IBP reduction code Kira across 16 integrals of varying complexity. While SAILIR is slower in wall-clock time, its per-worker memory consumption remains approximately flat regardless of integral complexity, in contrast to Kira whose memory grows rapidly with complexity. For the most complex integrals considered here, SAILIR uses only 40\% of the memory of Kira while achieving comparable reduction times. This demonstrates a fundamentally new paradigm for IBP reduction in which the memory bottleneck of Laporta-based approaches could be entirely overcome, potentially opening the door to precision calculations that are currently intractable.

    hep-phcs.LGhep-th8 citations
30. 30*

    Aspects of a Five-Dimensional $U(1{)}_{L_{\mu }-L_{\tau }}$ Model at Future Muon-Based Colliders

    Dibyendu Chakraborty🇮🇳 · Arindam Chatterjee🇮🇳 · AseshKrishna Datta🇮🇳 · Ayushi Kaushik🇮🇳 · Kenji Nishiwaki🇮🇳

    We study a five-dimensional (5D) framework based on the $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge symmetry, where the associated gauge field $V$ propagates in the bulk, giving rise to an infinite tower of Kaluza--Klein (KK) excitations $V^{(n)}$ that couple selectively to the second- and third-generation leptons. Originally motivated by its potential to address the muon $g-2$ anomaly, this framework remains of interest as a minimal, anomaly-free, phenomenologically well-motivated extension of the Standard Model (SM) of particle physics. We focus on high-energy muon-based colliders, which could directly probe the gauge structure without relying on the kinetic mixing between the SM hypercharge gauge boson and the 5D gauge boson $V$. We explore a set of complementary processes: the elastic ${\mu }^{+}{\mu }^{+}\to {\mu }^{+}{\mu }^{+}$ scattering via off-shell exchange of KK (gauge) excitations $V^{(n)}$; the bremsstrahlung production of $V^{(n)}$ followed by their decays into neutrinos and into ${\mu }^{-}{\mu }^{+}$ at a future $\mu$TRISTAN collider. Further, we study the ${\mu }^{-}{\mu }^{+}\to {\mu }^{-}{\mu }^{+}$ scattering via resonant KK excitation(s) at a future muon collider. Our results show that these future muon-based colliders could offer sensitive and complementary probes into regions in the parameter space of the scenario that are beyond the reach of low-energy experiments. In particular, such experiments would be able to probe both heavier such KK gauge bosons with TeV-scale masses for relatively large gauge couplings, as well as the much lighter ones with masses in the MeV-scale for couplings as weak as $g_D\sim \mathcal{O}(10^{-5})$, thereby offering a promising $2\sigma$ exclusion reach for such KK excitations, over an extensive range of masses, at these facilities.

    hep-ph1 citation
31. 31*

    The chromomagnetic moment of a heavy quark with hyperasymptotic precision

    Cesar Ayala🇨🇱 · Antonio Pineda🇪🇸

    We determine the normalization of the leading infrared renormalon of the chromomagnetic moment of a heavy quark. Estimates of higher order coefficients of the perturbative series are given. We compute the hyperfine splitting of the $B$ and $D$ mesons for the ground state with hyperasymptotic precision by including the leading terminant, associated with the first infrared renormalon. We fit the experimental data to the operator product expansion theoretical prediction with ${\hat{\mu }}_{G,\mathrm{PV}}^2$ as the free parameter. We obtain ${\hat{\mu }}_{G,\mathrm{PV}}^2=0.507(7)$ GeV${}^2$ for the ground state.

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

    Is the $w_0{w}_a$CDM cosmological parameterization evidence for dark energy dynamics partially caused by the excess smoothing of Planck PR4 CMB anisotropy data?

    Javier de Cruz Pérez🇪🇸 · Chan-Gyung Park🇰🇷 · Bharat Ratra🇺🇸

    We study the performance of the flat $\Lambda$CDM model and the dynamical dark energy parameterizations $w_0$CDM and $w_0{w}_a$CDM, in which the dark energy (DE) equation of state is either constant ($w=w_0$) or redshift-dependent [$w(z)=w_0+w_{a}z/(1+z)$], without and with a varying CMB lensing consistency parameter $A_L$, using combinations of Planck PR4 CMB data (PR4 and lensing), and a compilation of non-CMB data composed of baryon acoustic oscillation (BAO) data that do not include DESI BAO data, Pantheon+ type Ia supernova observations, Hubble parameter measurements $H(z)$, and growth rate $f{\sigma }_8$ data. We also compare results from earlier Planck PR3 data with those obtained using PR4 data in order to assess the stability of cosmological constraints. For the largest data combinations, PR3/PR4+lensing+non-CMB, the cosmological parameters inferred from PR3 and PR4 data are consistent, almost all differing by $1\sigma$ or less. For the $\Lambda$CDM$+A_L$ model, we have $A_L=1.087\pm 0.035$ for PR3 and $A_L=1.053\pm 0.034$ ($1.6\sigma$ above unity) for PR4, which indicates that the CMB lensing anomaly is reduced when PR4 data are used. For the $w_0{w}_a$CDM parameterization, we find $w_0=-0.863\pm 0.060$ (quintessence-like) and $w_0+w_a=-1.37_{-0.17}^{+0.19}$ (phantom-like), suggesting that the current observations favor dynamical DE over a cosmological constant at about $1.8\sigma$. For the $w_0{w}_a$CDM$+A_L$ parameterization, we find $w_0=-0.877\pm 0.060$ and $w_0+w_a=-1.29_{-0.17}^{+0.20}$, corresponding to a preference for dynamical DE over a cosmological constant of about $1.5\sigma$ and with $A_L=1.042\pm 0.037$ exceeding unity at $1.1\sigma$. These results indicate that while the PR4 data mildly favor a time-evolving DE, part of this preference may be associated with possible residual excess smoothing present in the Planck PR4 CMB anisotropy spectra (abridged).

    ↳ astro-ph.COgr-qchep-phhep-th8 citations
33. 33*

    Anisotropic Flow of light (anti-)(hyper-)nuclei in Pb+Pb Collision at $\sqrt{s_{NN}}=5.36$ TeV

    Fu Ma · Zheng-Qing Wang · Xiong-Hong He · Che Ming Ko · Qi-Ye Shou · Kai-Jia Sun · Wenbin Zhao · Wen-Hao Zhou

    Using the coalescence model with nucleon phase-space distributions generated by the hybrid MUSIC framework, we study the elliptic flow ($v_2$) and triangular flow ($v_3$) of (anti-)protons, (anti-)deuterons, (anti-)${}^3\mathrm{He}$, and ${}_{\Lambda }^3\mathrm{H}$ in Pb+Pb collisions at $\sqrt{s_{NN}}=5.36$ TeV. We find that the simple $v_2$ scaling with the number of constituent nucleons $A$ breaks down at high transverse momentum $p_T/A>1.5$ GeV/$c$, while an improved scaling relation holds well up to $p_T/A\approx 3$ GeV/$c$. In contrast, $v_3$ exhibits similar behavior under both scaling prescriptions, with no significant difference. We also make predictions for $v_2$ and $v_3$ of the hypertriton and find these flows are insensitive to the Lambda-deuteron ($\Lambda -d$) distance inside the hypertriton. Our results are compared with preliminary experimental measurements by the ALICE Collaboration and offer insight into the production mechanisms of light (anti-)(hyper-)nuclei in high-energy heavy-ion collisions.

    ↳ nucl-thhep-phPLB(2026)·1 citation
34. 34*

    Heavy and heavy-light tensor and axial-tensor mesons in the Covariant Spectator Theory

    Elmar P. Biernat🇵🇹 · Alfred Stadler🇵🇹

    We present the first calculation of tensor and axial-tensor mesons with total spin $J\ge 2$ within the Covariant Spectator Theory. We employ a refined quark-antiquark interaction kernel that incorporates the momentum dependence of the strong coupling, replacing the previously used constant term of the kernel. Global least-squares fits to the masses of experimentally established heavy and heavy-light meson states yield an excellent description of the mass spectrum for $J^P=0^{\pm },1^{\pm },2^{\pm }$, and $3^{\pm }$ using only eight adjustable parameters.

    ↳ nucl-thhep-phActa Phys.Polon.Supp.(2026)·1 citation
35. 35*

    Disentangling Flow Contributions from the Chiral Magnetic Effect in U+U Collisions with Forward-Backward Multiplicity Asymmetry

    Kaiser Shafi🇮🇳 · Sandeep Chatterjee🇮🇳

    The observation of the Chiral Magnetic Effect (CME) in heavy-ion collisions remains challenging because of large flow-induced backgrounds and experimental constraints. We demonstrate that the forward-backward multiplicity asymmetry (FBMA) provides a robust and experimentally accessible control parameter to separate the flow background from CME signal in the collisions of deformed nuclei, such as prolate uranium where FBMA is naturally enhanced and correlated with the initial-state geometry. Monte Carlo Glauber simulations indicate that varying FBMA within a fixed centrality class modulates ellipticity largely independently of the magnetic-field correlator, establishing FBMA as a practical tool for disentangling CME signals from flow driven background.

    ↳ nucl-thhep-phhep-th0 citations
36. 36*

    Causality, the Kovtun-Son-Starinets bound, and a novel sum rule for spectral densities

    G. Yu. Prokhorov🇷🇺 · O. V. Teryaev🇷🇺

    We directly show that the local ratio of the shear viscosity to the entropy density for Unruh radiation at a finite distance from the horizon is universal and satisfies the relation $\eta /s=1/(4\pi c_s^2)$, which involves the speed of sound $c_s$. Since $c_s^2\le 1$ by causality, this establishes the close connection between the famous Kovtun-Son-Starinets bound and causality. Moreover, we show that the ratio of bulk to shear viscosity saturates another well-known bound for the bulk viscosity, predicted within holographic approach. We also show that the condition of isotropy of thermal radiation in the Rindler space leads to a novel sum rule relating the $c^{(0)}(\mu )$ and $c^{(2)}(\mu )$ spectral densities, and we explicitly demonstrate its validity for conformal field theory and free massive Dirac fields in any number of dimensions. The sum rule provides the validity of Pascal law and bears some similarity with Burkhardt-Cottingham sum rule for spin-dependent parton distributions. Our result suggests a new perspective on dissipative transport phenomena in media undergoing extreme acceleration, such as quark-gluon plasma created in relativistic heavy-ion collisions.

    ↳ hep-thhep-phnucl-th1 citation
37. 37*

    Anomalies in family unification models from bordism classification

    Tsubasa Sugeno🇯🇵 · Hiroki Wada🇯🇵

    We study anomalies in family unification models within the framework of the bordism classification of invertible field theories. These models are based on four-dimensional $\mathcal{N}=1$ supersymmetric nonlinear sigma models, in which the three generations of quarks and leptons arise as superpartners of the sigma model fields. We focus on models whose target spaces are constructed from the exceptional group $E_7$ and its subgroups. For the consistency of the theory, sigma model anomalies must be cancelled. We show the absence of global sigma model anomalies, which are encoded in the torsion part of the relevant bordism groups, by explicitly computing these groups using the Atiyah-Hirzebruch spectral sequence. In constructing family unification models, symmetries acting on the coset spaces are gauged, which may introduce additional anomalies. We identify the relevant bordism groups in this setting and demonstrate that no global anomalies arise when the isotropy subgroup of the coset space is gauged.

    ↳ hep-thhep-ph0 citations
38. 38*

    Information-Geometric Perspective on the Hubble Tension: Eigenmode Rotation and Curvature Suppression in wCDM

    Seokcheon Lee

    The Hubble tension is shaped not only by shifts between early- and late-time parameter estimates, but also by the stiffness of the constraints that define them. In this work, we analyze this geometric structure in the wCDM model by separating the discrepancy into two components: a parameter displacement and a directional Fisher curvature. Within the local Gaussian approximation, the quadratic tension along a given direction factorizes into the squared shift and the combined directional curvature contributed by the datasets. Applying this framework to Planck, DESI DR2, and SH0ES, we show that extending \LambdaCDM to wCDM primarily reshapes the Fisher geometry of the CMB constraint rather than opening a genuinely new route to concordance. Allowing the dark-energy equation-of-state parameter w to vary suppresses the leading Planck Fisher eigenvalue to only \sim 2.7 % of its \LambdaCDM value, while producing only a modest rotation of the dominant acoustic-scale eigenmode. The net effect is a strong softening of the effective acoustic rigidity. At the same time, high-precision late-time data, especially from DESI DR2, inject substantial curvature along the expansion-rate direction. This added stiffness acts as a geometric wall, closing off phantom-like escape routes and sharply limiting tension relief within the extended parameter space. Our results indicate that changes in the inferred H_0 tension under model extension are best understood as a reconfiguration of the constraint manifold rather than as evidence for new physical agreement. The shift-curvature decomposition thus offers a simple, fast, and physically transparent way to diagnose cosmological tensions.

    ↳ astro-ph.COhep-ph2 citations
39. 39*

    Lattice studies of chimera baryons in Sp(4) gauge theory

    Jong-Wan Lee🇰🇷 · Ed Bennett🇺🇸 · Luigi Del Debbio🇬🇧 · Niccolò Forzano🇬🇧 · Ryan C. Hill🇬🇧 · Deog Ki Hong🇰🇷 · Ho Hsiao🇯🇵 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Alessandro Lupo🇫🇷 · Maurizio Piai🇬🇧 · Davide Vadacchino🇬🇧 · Fabian Zierler🇬🇧

    We study chimera baryons, fermion bound states composed of two (hyper)quarks transforming in the fundamental and one in the antisymmetric representation of a non-Abelian gauge group. While in QCD they coincide with ordinary baryons, in composite Higgs models (CHMs) with top partial compositeness, spin-1/2 chimera baryons serve as partners of the top quark and are responsible for its large mass. We perform non-perturbative lattice calculations of the low-lying spectrum of the chimera baryons, in a specific realization of CHMs based on a Sp(4) gauge theory. In the quenched approximation, we present the numerical results in the continuum and massless limits. Then, for dynamical fermions, we measure the spectrum and matrix elements by employing a newly developed spectral density analysis for several choices of the lattice parameters.

    ↳ hep-lathep-phnucl-thJ.Subatomic Part.Cosmol.(2026)·1 citation
40. 40*

    Dissipative spin hydrodynamics in Bjorken flow and thermal dilepton production

    Sejal Singh🇮🇳 · Sourav Dey🇮🇳 · Arpan Das🇮🇳 · Hiranmaya Mishra🇮🇳 · Amaresh Jaiswal🇮🇳

    We investigate the boost-invariant expansion of a recently developed first-order spin hydrodynamic framework in which the spin chemical potential is treated as a leading-order hydrodynamic variable. Considering a symmetric energy-momentum tensor and a separately conserved spin tensor, we derive the coupled evolution equations for the medium temperature and the independent components of the spin chemical potential in the presence of both viscous and spin-diffusive transport coefficients. For a boost-invariant system, only the magnetic-like components of the spin chemical potential survive, and their evolution is shown to depend sensitively on the spin transport coefficients. The transverse spin components decay more rapidly due to spin dissipation, while the longitudinal component survives for a longer duration. We further demonstrate that the evolution of the spin degrees of freedom modifies the temperature profile of the expanding medium. Using the resulting temperature profiles, we calculate thermal dilepton production rates from quark-antiquark annihilation. We find that the presence of spin dynamics enhances the dilepton yield relative to standard dissipative hydrodynamics, with the magnitude of the enhancement depending on the spin transport coefficients. Our results indicate that thermal dileptons can provide an indirect probe of spin dynamics and spin transport in the quark-gluon plasma.

    ↳ nucl-thhep-ph2 citations
41. 41*

    New Solutions for RG Equations in QCD

    R.M. Iakhibbaev🇷🇺 · D.I. Kazakov🇷🇺 · D.M. Tolkachev🇷🇺

    We construct simple analytical solutions of renormalization group equations for the running coupling and for the Green functions in QCD in the asymptotic regime. These solutions have an explicit form and subsequently sum up the leading, subleading, and so on logarithms in all orders of PT. They easily reproduce the inverse logarithm expansion and allow for further summation and improvement of the asymptotic behaviour.

    ↳ hep-thhep-phPLB(2026)·1 citation
42. 42*

    Feynman integral reduction with intersection theory made simple

    Li-Hong Huang (2)🇨🇳 · Yan-Qing Ma (2)🇨🇳 · Ziwen Wang (1)🇨🇳 · Li Lin Yang (1) ((1) Zhejiang Institute of Modern Physics, School of Physics, Zhejiang University, Hangzhou, China, (2) School of Physics, Peking University, Beijing, China)🇨🇳

    Feynman integral reduction based on intersection theory provides an alternative to the traditional integration-by-parts method, yet its practical application has been constrained by the large number of variables required in the computation. In this Letter, we demonstrate that by employing the recently introduced branch representation, the reduction of $L$-loop Feynman integrals with an arbitrary number of external legs can be achieved through the computation of at most $(3L-3)$-variable intersection numbers. This constitutes a significant simplification compared to existing approaches, particularly for multi-leg integrals where the number of variables in conventional methods scales with the total number of propagators. We validate the proposed method through explicit calculations of two-loop diagrams, demonstrating substantial improvements in computational efficiency relative to both traditional intersection-theory approaches and standard integration-by-parts reduction techniques.

    ↳ hep-thhep-ph5 citations
43. 43*

    Relativistic Barnett effect and Curie law in a rigidly rotating free Fermi gas

    M. Abedlou Ahadi🇮🇷 · N. Sadooghi🇮🇷

    By combining methods from thermal field theory and statistical mechanics, we reexamine the spin polarization caused by the relativistic Barnett effect in a rigidly rotating Fermi gas. We determine the pressure of this medium and show that it depends on an effective chemical potential, which includes contributions from orbital angular momentum-rotation and spin-rotation coupling. We introduce a specific regularization scheme to sum over the angular momentum quantum numbers. As a result, the thermal pressure and all thermodynamic quantities are separated into two parts that differ only in the spin fugacities of spin-up and spin-down fermions. We calculate the Fermi energy for both components and show that the Fermi energy of the spin-down fermions is lower than that of the spin-up ones. This difference arises from the spin-rotation coupling and leads to a spin polarization consistent with the Barnett effect. In particular, we introduce the spin-chemicorotational ratio $\eta \equiv {\Omega }^{(0)}/2{\mu }^{(0)}$, which adjusts the spin polarization of the Fermi gas. Here, ${\Omega }^{(0)}$ and ${\mu }^{(0)}$ represent the angular velocity and chemical potential at zero temperature, respectively. The factor $1/2$ accounts for the fermion's spin. We explore the temperature dependence of $\mu$ and $\Omega$, while assuming that the number of spin-up and spin-down fermions remains temperature independent. Our findings indicate that the spin-down component of the rotating Fermi gas dilutes at lower temperatures compared to the spin-up component. Additionally, we calculate the magnetic susceptibility arising from the Barnett magnetization and demonstrate that it is proportional to the moment of inertia $I$ of the rotating Fermi gas. Finally, we prove that $I$ exhibits a $1/T$ behavior in the high-temperature limit, similar to the Curie law of paramagnetism.

    ↳ nucl-thcond-mat.quant-gashep-ph0 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.