Thu·Apr 2, 2026Thursday·April 2, 2026

1. 01*

   Light-by-light scattering: asymptotic expansions, Coulomb resummation and NLO corrections

   Ajjath A H · Ekta Chaubey🇩🇪 · Hua-Sheng Shao🇫🇷

   Light-by-light (LbL) scattering is one of the earliest predictions of quantum electrodynamics (QED). Interest in this process has been renewed following its experimental observation at the LHC and the prospects of future measurements at free-electron laser facilities. In this paper, we refine theoretical predictions for LbL scattering by improving the full fermion-mass-dependent two-loop QCD and QED helicity amplitudes using high- and low-energy asymptotic expansions, and by performing Coulomb resummation in the threshold region. We present state-of-the-art predictions for LbL cross sections in the Standard Model and provide a new event generator, LbLatNLO, for Monte Carlo simulations of LbL scattering.

   hep-phhep-exhep-thnucl-ex+11 citation
2. 02*

   Full positivity bounds for anomalous quartic gauge couplings in SMEFT

   Fu-Ming Chang🇨🇳 · Zhuo-Yan Chen🇨🇳 · Shuang-Yong Zhou🇨🇳

   Electroweak boson scattering at the LHC provides a crucial avenue for probing physics beyond the Standard Model, particularly regarding deviations in quartic gauge couplings. We derive the complete set of positivity bounds for the $22$ dimension-$8$ anomalous quartic gauge coupling (aQGC) coefficients within the Standard Model Effective Field Theory (SMEFT). Moving beyond previous studies limited to transverse vector bosons, our analysis incorporates all electroweak boson modes, explicitly constructing the extremal rays (ERs) of the positivity cone through a group theoretic framework. We utilize two independent methods--direct construction and Casimir operator analysis--to determine these rays, addressing complexities such as parity-violating operators and continuous parameter degeneracies. Our results indicate that the positivity bounds impose severe constraints, restricting the physically viable parameter space to approximately $0.0313\%$ of the naive total space. Furthermore, we derive linear analytical bounds for various operator combinations and provide an easy-to-use Python package, {\tt SMEFTaQGC}, which implements algorithms to numerically verify positivity and compute the optimized positivity bounds for general aQGC configurations.

   hep-phhep-th4 citations
3. 03*

   Lectures on Light Particles and Compact Objects

   Alessandro Lella🇮🇹 · Jamie McDonald🇬🇧

   This document is based on lectures delivered at a recent COSMIC WISPers COST Action training school in Annecy in September 2025. They examine detection of weakly interacting slim particles (WISPs), specifically axions and high-frequency gravitational waves, with compact objects. These slightly expanded notes focus on searches for axion dark matter and axion-like particles with neutron stars, superradiance, white dwarfs and astrophysical searches for high-frequency gravitational waves. They are accompanied by a set of practical exercises. Comments on these notes are gratefully received.

   hep-phastro-ph.COPoS(2026)·0 citations
4. 04*

   A Pati-Salam realization of the Nelson-Barr mechanism

   Clara Murgui🇨🇭

   We present a UV completion of the Standard Model in which quarks and leptons are unified under color SU(4). A single fermionic representation, the real antisymmetric, provides the building blocks to address the strong CP problem via the Nelson-Barr mechanism, while simultaneously correcting the charged-lepton and down-quark mass relations predicted by Pati-Salam theories for the two heaviest generations. We show that the characteristic scales of the theory are strongly constrained by its phenomenology. The interplay between the quality of the Nelson-Barr mechanism and the non-observation of baryon-number-violating processes determines the scale of spontaneous CP violation and the mass of the new vector-like down quark, while the mass of the Standard Model down quark and the upper bound on neutrino masses fix the quark-lepton unification scale. The theory predicts a distinctive baryon-number-violating decay mode of the neutron, $n\to K^{+}{\ell }^{-}$ (with $\ell =e,\mu$), which lies within the projected sensitivity of upcoming nucleon-decay experiments such as Hyper-Kamiokande and DUNE.

   hep-ph1 citation
5. 05*

   Next-to-Minimal Freeze-in Dark Matter

   Nicolás Bernal🇦🇪 · Sagnik Mukherjee🇺🇸 · James Unwin🇺🇸

   If the dark matter mass exceeds the highest temperature of the thermal bath, then dark matter production is Boltzmann suppressed. This opens new possibilities for dark matter model building. In particular, WIMP models that are experimentally excluded can be revived in this setting; conversely, freeze-in models, which would typically be beyond experimental reach, are potentially discoverable in the Boltzmann suppressed regime. In a recent letter, we highlighted these aspects for the case of electroweak doublet fermion dark matter assuming instantaneous inflationary reheating. Due to its elegance and simplicity, we coin this {\em Minimal Freeze-in} (MFI) Dark Matter. Here we consider next-to-minimal extensions of MFI dark matter. We present the implications for non-instantaneous reheating, including scenarios beyond the standard picture in which the Universe is initially matter dominated prior to reheating. Furthermore, we explore model variations within the electroweak dark matter scenario. Specifically, we consider fermion dark matter in higher representations of SU(2)${}_L$, exploring the current limits and the near-future discovery potential.

   hep-phastro-ph.COPRD(2026)·1 citation
6. 06*

   Dilepton Correlations from Heavy Flavor Decays

   T. Dahms🇩🇪 · R. Vogt🇺🇸

   Background: Azimuthal correlations between heavy flavor hadrons have been previously studied in $p+p$ collisions (Phys. Rev. C {\bf 98}, 034907 (2018), {\bf 101}, 034910 (2020)). These studies found good agreement with the data and provide a baseline for further studies in $p+A$ and $A+A$ collisions. Purpose: This work extends those studies to heavy flavor hadron decays to low mass lepton pairs. The low mass dilepton region is important for heavy ion collisions because of the interest in thermal dilepton production as a signature of the early time dynamics of the medium. Methods: Building on previous work, azimuthal correlations between leptons from semileptonic decays of heavy flavor hadrons are examined. The exclusive \textsc{HVQMNR} code is used in the calculations, made in the PHENIX acceptance at $\sqrt{s}=200$~GeV and for dielectrons in ALICE at $\sqrt{s}=13$~TeV. The $b\overline{b}$ decay contributions subtract like-sign lepton pairs from the opposite-sign signal. Results: The next-to-leading order calculations reproduce the trends of the PHENIX data. The calculations at 13~TeV show a change in signal as electron pair $p_T$ is increased, with the peak of the $\Delta \varphi$ distribution moving from $\Delta \varphi \sim \pi$ to $\sim 0$ and the contribution from bottom decays becoming dominant. The sensitivity of the signal to $k_T$ broadening is also studied and found to be small. Conclusions: It is found that the dependence on $k_T$ broadening previously observed is significantly reduced by the decay process. Despite this, the correlations between decay leptons retains some memory of the correlations between the parent hadrons in $p+p$ collisions. However, to study these correlations in heavy-ion collisions, it is necessary to separate them from thermal dilepton production in the same mass region.

   hep-ph0 citations
7. 07*

   Motivation and design of a yotta-eV ${\tau }^{+}{\tau }^{-}$ collider

   Matt Bellis · Matthew Carberg · Chester Gould🇦🇺 · Jackson Ingenito · Fasiha Khaliq · Emely Kintzel · Shane Kirschmann · Neha Matta · Sophia Pavia · Emmett Pearl · Payton Ramsdill · Grace Scherer · Cullen Wright

   Two significant goals of the particle physics community is the precision study of the Higgs boson and the search for new particles. The Large Hadron Collider (LHC) is the current high-energy collider, soon to be superseded by the High-Luminosity LHC (HL-LHC). Much of the community has rallied around a muon-collider, though that is most likely 25 years in the future. In this paper, we argue for a bolder approach: {\it a tau-collider}, in which oppositely-charged $\tau$-leptons are collided with energies on the yotta-eV scale and a potential radius that places it in the Oort cloud. Given the long time-scale and significant construction challenges, we strongly suggest the focus of the community shift to this discovery machine. We acknowledge that the technology necessary may require humanity to evolve to a Kardashev Level-I or Level-II civilization, which is all the more reason to begin R\&D now.

   hep-phhep-exphysics.ed-ph0 citations
8. 08*

   Universal features of high-energy scattering of Laguerre-Gaussian states

   Yaoqi Yang🇨🇳 · Igor P. Ivanov🇨🇳

   Vortex states of photons, electrons, and other particles are wave packets that carry intrinsic orbital angular momentum (OAM) and exhibit other features unavailable for plane waves. Collisions of high-energy vortex states can become a promising tool for nuclear and particle physics, once experimental challenges are overcome. An extensive literature exists on scattering processes involving vortex states; however, most works rely on assumptions that will be challenging to achieve in experiment. In this work, we initiate a systematic re-analysis of vortex-state scattering processes using paraxial Laguerre-Gaussian (LG) wave packets colliding at a non-zero impact parameter $b$. Since the total final transverse momentum $P_{\perp }$ is no longer fixed, we focus on how the differential cross section depends on $P_{\perp }$. We emphasize that non-trivial $P_{\perp }$-dependent features can originate either from the shape of the LG wave packets or from the dynamics of the scattering process under interest. Here, we focus on the former source and explore in detail these universal kinematic features, while the study of process-specific modifications, along with the novel insights they may bring, is delegated to a future work. Interestingly, the non-zero impact parameter $b$ plays a key role in many $P_{\perp }$-dependent effects, making it a useful probe of vortex states, not a nuisance factor as often assumed.

   hep-phquant-phPRD(2026)·3 citations
9. 09*

   Searching for New Physics Inside Jets with the Herwig 7 Generalised Parton Shower

   Taehee Kim🇰🇷 · Joon-Bin Lee🇰🇷 · M.R. Masouminia🇬🇧 · Michael H. Seymour🇬🇧 · Un-ki Yang🇰🇷

   This study investigates parton shower evolution incorporating both Standard Model (SM) and beyond-the-Standard-Model (BSM) radiation, focusing on the phenomenology of a massive $Z^{\prime }$ boson. While traditional approaches typically assume direct $Z^{\prime }$ production in the hard process, the possibility of $Z^{\prime }$ production within jets, enabled by subsequent emissions in the parton shower, offers a complementary opportunity to probe new physics through jet substructure and event topology. The newly developed Herwig 7 framework supporting BSM parton showers enables efficient simulation of $Z^{\prime }$ production in the logarithmically enhanced regime. Using a simple BSM benchmark, the minimal $U(1{)}_{B-L}$ extension of the SM, the interplay between the SM and BSM showers is evaluated to identify kinematic features that distinguish $Z^{\prime }$-induced jets from conventional signatures. BSM-radiation signatures are contrasted with SM backgrounds such as QCD, top-quark, and Drell-Yan production, identifying potential discriminants for experimental searches. Experimental sensitivity at the LHC and prospective future colliders is estimated via statistical-significance projections. We find that $Z^{\prime }$ bosons produced through parton shower radiation populate non-isolated regions inside jets, providing an avenue for new-physics searches overlooked in traditional analyses.

   hep-ph1 citation
10. 10*

    Hyperon non-leptonic decays in relativistic Chiral Perturbation Theory with resonances

    Nora Salone (1)🇵🇱 · Fernando Alvarado (2)🇩🇪 · Stefan Leupold (3)🇸🇪 · Andrzej Kupsc (3 and 4) ((1) University of Silesia in Katowice, Poland, (2) GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, (3) Uppsala universitet, Sweden, (4) National Centre for Nuclear Research, Poland)🇸🇪

    Motivated by recent experimental advances in the corresponding measurements, non-leptonic hyperon decays are calculated, for the first time in a relativistic manner, in Chiral Perturbation Theory at next-to-leading order (NLO). On the one hand, relativistic loop corrections are computed explicitly based on the ground-state octet and decuplet fields. On the other hand, the NLO weak-transition low-energy constants are estimated by resonance saturation, inspired by the non-relativistic tree-level computation of Ref. [1]. In particular, the $1/2^{-}$ and the (excited) $1/2^{+}$ resonance octets are utilized. The remaining unknown parameters are fitted to the decay amplitudes. A good combined fit to both $s$- and $p$-wave amplitudes is achieved with the caveat of not being very tightly constrained. The role of the resonances is found to be crucial. Consequences for further investigations and open questions are addressed.

    hep-ph1 citation
11. 11*

    Baryogenesis in $SU(2{)}_L$ multiplet models

    Kiyoto Ogawa🇯🇵 · Masanori Tanaka🇨🇳

    We investigate baryogenesis in Standard Model (SM) extensions with new $SU(2{)}_L$ multiplet fields. We focus on sphalerogenesis, in which the baryon asymmetry of the Universe (BAU) is generated through the gradual decoupling of CP-violating electroweak sphaleron-like processes. We show that the observed BAU can be reproduced when the new fields possess CP-violating Yukawa interactions, which leave a CP-violating dimension-six operator involving the $SU(2{)}_L$ gauge fields at low energies. As representative examples, we study models with fermionic $SU(2{)}_L$ quintuplets and septuplets, and find that these field masses should be $\mathcal{O}(1)\mathrm{TeV}$ to explain the BAU. We also show that viable parameter regions for the BAU are consistent with current bounds on the electron electric dipole moment and thoroughly probed by future measurements such as ACME III and by mono-lepton searches at the HL-LHC. Our results provide a concrete and phenomenologically testable ultraviolet completion of sphalerogenesis.

    hep-phastro-ph.COJHEP(2026)·2 citations
12. 12*

    Charged current induced electron-proton scattering and the axial vector form factor

    A. Fatima🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳

    We investigate the total scattering cross section($\sigma$), the differential cross section$\left(\frac{d\sigma }{d{Q}^2}\right)$, the longitudinal($A_L(E_e,Q^2)$) and perpendicular($A_P(E_e,Q^2)$) spin asymmetries of the polarized target proton, as well as the longitudinal($P_L(E_e,Q^2)$), perpendicular($P_P(E_e,Q^2)$), and transverse($P_T(E_e,Q^2)$) polarization components of the final neutron, in the weak charged current induced electron-proton scattering relevant to the future experiments at the Thomas Jefferson National Accelerator Facility(JLab) and Mainz Microtron(MAMI). The analysis is performed assuming time-reversal(T) invariance as well as without assuming T invariance, allowing for a nonvanishing transverse polarization component of the final nucleon, perpendicular to the production plane. Numerical results are presented for the above mentioned observables, and their sensitivities to the various parameterizations of the axial vector form factor $g_1(Q^2)$ and a nonzero weak electric form factor $g_2(Q^2)$ are examined. We find that the cross section depends strongly on the parameterizations used for the axial vector form factor. Moreover, the dipole parameterization of $g_1(Q^2)$ with a higher value of the axial dipole mass $M_A$ simulates the apparent enhancement in $\sigma$ obtained using the non-dipole parameterizations like the $z$-expansion and Faddeev equation form. The cross sections are found to depend only weakly on the weak electric form factor $g_2(Q^2)$, which is associated with the violation of G-invariance. On the contrary, the spin observables both $A_{L,P}(E_e,Q^2)$ and $P_{L,P}(E_e,Q^2)$ are found to be strongly dependent on $g_2(Q^2)$. This study may be useful in the analysis of the neutrino oscillation experiments to provide an alternative constrain on the parameterization of axial vector form factor, which currently has large uncertainties.

    hep-phhep-exPRD(2026)·2 citations
13. 13*

    Signatures of Long-Lived Heavy Neutral Leptons from Neutrinophilic Charged Higgs Pair Production at the LHC

    Nobuchika Okada🇺🇸 · Prasenjit Sanyal🇰🇷 · Ravindra Kumar Verma🇫🇮

    In the neutrinophilic Higgs doublet framework, the neutrino Dirac Yukawa couplings can be sizable because of the small vacuum expection value of the extra Higgs doublet, even for a low seesaw scale. Due to this structure, the neutrinophilic charged Higgs bosons, once created, decay dominantly into heavy neutral leptons (HNLs) and charged leptons. This is a new mechanism to produce a gauge singlet HNL without suppressed cross sections. In the standard seesaw, one HNL can be long-lived, when the lightest neutrino is sufficiently light. We investigate displaced vertex signatures of the long-lived HNLs produced from the decays of the charged Higgs pair at the high luminosity LHC. We consider one displaced vertex as well as two displaced vertices signatures and perform a dedicated simulation to identify the displaced leptons. We find that high statistical significance can be achieved for the observation of one displaced vertex for charged Higgs pair production cross section $>\mathcal{O}(1)$ fb. On the other hand, the observation of two displaced vertices is challenging even for charged Higgs pair production cross section of $\mathcal{O}(10)$ fb.

    hep-phhep-ex2 citations
14. 14*

    $t\bar{t}$ production as a probe of dimension-6 SMEFT at higher orders

    Nikolaos Kidonakis🇺🇸 · Kaan Şimşek🇺🇸

    We study top-antitop pair production in proton-proton collisions within the Standard Model Effective Field Theory (SMEFT) at dimension 6. We focus on the top chromomagnetic operator $C_{tG}$ together with the four-quark operators relevant for unpolarized $t\bar{t}$ production. We analyze the top-quark single-differential transverse-momentum ($p_T$) and rapidity ($y$) distributions and the double-differential distributions in $p_T$ and $y$ ($p_T\times y$) at 13~TeV, and we present projections for 13.6~TeV using the same binning. Our highest-order setup combines next-to-next-to-leading-order (NNLO) Standard Model (SM) predictions with approximate NNLO (aNNLO) SM--SMEFT interference corrections. We find that higher-order QCD effects are essential for a stable SMEFT interpretation, yielding substantially more robust bounds and milder parameter degeneracies. The strongest sensitivity is obtained for $C_{tG}$. In the combined highest-order analysis of the 13-TeV results and 13.6-TeV projections, we obtain sensitivity to effective scales up to 3.9~TeV. Our results show that higher-order differential top-pair production provides a precise and theoretically controlled probe of the top chromomagnetic interaction.

    hep-ph0 citations
15. 15*

    Renormalization-group-improved constraints on dimension-7 baryon-number-violating operators

    Yi Liao🇨🇳 · Xiao-Dong Ma🇨🇳 · Xiang Zhao🇨🇳

    We study constraints on dimension-7 SMEFT baryon-number-violating operators from nucleon decays by incorporating full renormalization group (RG) running effects. At high new physics scales, we demonstrate that RG running effects help set stringent bounds on all 297 Wilson coefficients compared to the tree-level analysis in which only coefficients involving the first and second fermion generations could be constrained. Our findings highlight that the RG running effects through Yukawa mixings are particularly important for indirectly probing operators involving the second and third generation fermions.

    hep-phPLB(2026)·2 citations
16. 16*

    Baryonic form factors of light pseudoscalar mesons

    A.S. Miramontes🇪🇸 · J.M. Morgado🇪🇸 · J. Papavassiliou🇪🇸

    Employing the Bethe-Salpeter formalism, we present a computation of the space-like baryonic form factor for the pion and kaon. In the exact isospin-symmetric limit this observable is forbidden by $G$-parity, so that any nonzero signal constitutes a direct probe of the quark mass difference $m_d-m_u$. The form factors are evaluated in the impulse approximation using fully dressed quark propagators, meson Bethe-Salpeter amplitudes, and a dressed baryon-current vertex constrained by the vector Ward-Takahashi identity. The baryonic radius computed with this method for the pion is given by $⟨r_B^2{⟩}_{{\pi }^{+}}^{1/2}=0.043(2)$ fm, and is consistent with the available dispersive benchmarks. Our predictions for the kaons, namely $⟨r_B^2{⟩}_{K^{+}}^{1/2}=0.265(7)$ fm and $⟨r_B^2{⟩}_{K^0}^{1/2}=0.262(7)$ fm, indicate a larger spatial extent than in the pion case; these results have no dispersive counterparts, and are compatible with chiral QCD models.

    hep-phnucl-thPLB(2026)·2 citations
17. 17*

    Mass relations in heavy hadrons from Jensen-like inequalities

    Wen-Xuan Zhang🇨🇳 · Wen-Nian Liu🇨🇳 · Duojie Jia🇨🇳

    We demonstrate that mass inequalities for hadrons with one or more heavy quarks arise primarily from the concavity of binding energies in the quark model, reflecting short-range Coulombic interactions and long-range confinement. Empirical two-body bindings $B_{i\bar{j}}$ are extracted from spin-averaged meson masses, ensuring model independence and direct use of experimental data. Fitting these as functions of reduced mass ${\mu }_{ij}$ reveals a critical confinement scale of 1.34~fm where bindings turn positive. The concave $B(1/\mu )$ justifies Jensen-like inequalities under flavor permutation, reproducing relations like $m_{x\bar{y}}>\frac{1}{2}(m_{x\bar{x}}+m_{y\bar{y}})$ and baryon analogs, including $m_{xyz}>\frac{1}{3}(m_{xxx}+m_{yyy}+m_{zzz})$. Hadron mass decomposition validates $\Delta M_{\text{EXP}}\approx \Delta B+\Delta C$ with $\sigma \sim 2.07$~MeV for mesons and baryons. Promoting inequalities to equalities, we predict masses for unobserved heavy baryons (e.g., $M({\Omega }_b^{\ast })=6076.6$MeV, $M({\Xi }_{cc}^{\ast })=3703.6$MeV and $M({\Omega }_{cc}^{\ast })=3802.4$MeV) and identify favored quark-exchange scattering channels.

    hep-ph0 citations
18. 18*

    Electromagnetic form factors of heavy-light pseudoscalar mesons

    A.S. Miramontes🇪🇸 · J. Papavassiliou🇪🇸 · J.M. Pawlowski🇩🇪

    We report calculations of space-like electromagnetic form factors and charge radii of pseudoscalar mesons, covering both light and heavy-light flavour sectors within a flavour-dependent Bethe-Salpeter framework.

    hep-phnucl-thActa Phys.Polon.Supp.(2026)·1 citation
19. 19*

    How uncertain are model predictions for the muon content of extensive air showers

    Sergey Ostapchenko🇩🇪

    The relation of model predictions for muon content of extensive air showers (EAS) to particular properties of hadron-air interactions is discussed. Further, using a new Monte Carlo generator of cosmic ray interactions, QGSb, the relevance of particular interaction mechanisms to the predicted EAS muon number is studied in some detail. The corresponding constraints imposed by accelerator measurements are discussed as well.

    hep-ph0 citations
20. 20*

    Quantum effects on neutrino parameters from a flavored gauge boson

    Alejandro Ibarra🇩🇪 · Lukas Treuer🇩🇪

    We calculate the one-loop renormalization group equations of the neutrino mass matrix when the Standard Model particle content is extended with a massive gauge boson which has family-dependent couplings to the left-handed leptons. We show that quantum effects induced by the extra gauge boson increase the rank of the neutrino mass matrix at the one-loop level, in contrast to the well-known result that Standard Model fields can only increase the rank at the two-loop level. We also discuss the possibility of generating dynamically the measured mass differences and mixing angles between the active neutrinos in scenarios with normal and inverted mass ordering.

    hep-phhep-thJHEP(2026)·1 citation
21. 21*

    Pions reloaded

    M.N. Ferreira🇧🇷 · A.S. Miramontes🇪🇸 · J.M. Morgado🇪🇸 · J. Papavassiliou🇪🇸 · J.M. Pawlowski🇩🇪

    We present a novel version of the pion Bethe-Salpeter equation in the chiral limit, solved using as ingredients state-of-the-art QCD correlation functions. The constraints imposed by the axial Ward-Takahashi identities are exactly fulfilled, both formally and numerically.

    hep-phnucl-thActa Phys.Polon.Supp.(2026)·0 citations
22. 22*

    Precise theoretical prediction on branching fractions and polarizations of $D\to VV$ decays

    Jing Ou-Yang🇨🇳 · Hui Zheng🇨🇳 · Run-Hui Li🇨🇳 · Si-Hong Zhou🇨🇳

    We present a precise and systematic analysis of $D\to VV$ decays within the factorization-assisted topological-amplitude approach, where $D$ denotes the set $\{D^0,D^{+},D_s^{+}\}$ and $V$ represents the vector mesons $\rho ,K^{\ast },\omega$, and $\varphi$. Given the limited current experimental data, the factorization-assisted topological-amplitude approach serves as a available phenomenological framework for predicting charmed meson decays to both vector mesons. In this framework, incorporating flavor SU(3) symmetry breaking effects, we can express nonfactorizable contributions of different modes as a minimal set of universal parameters globally fitted to experimental data. Utilizing 36 experimental data points for $D\to VV$ decays, we precisely extract ten nonfactorizable parameters associated with the $C$ and $E$ topological diagrams with ${\chi }^2/d.o.f.=8.43$. We find that a large strong phase in the longitude $E$ amplitude cause strong destructive interference with the $C$ longitudinal component, yielding $f_{\parallel }>f_L$, contrary to the naive factorization predictions. Additionally, for modes processing exclusively by the $E$ diagram, the amplitude hierarchy $|S|<|D|$ leads to a $D$-wave branching fraction larger than that of the $S$-wave. This explains recent observations that contradict $S$-wave dominance predictions. The predicted branching fractions and polarizations for 28 decay modes are consistent with existing experimental data. Unobserved modes, especially those with branching fractions of order $10^{-3}\sim 10^{-2}$, the $D$-wave dominated modes, and modes exhibiting $f_{\parallel }>f_L$, await measurement by BESIII, STCF, Belle II, and LHCb.

    hep-phPRD(2026)·1 citation
23. 23*

    Mass Hierarchies Without Mixing: Abelian Froggatt-Nielsen Models with Uncharged Left-Handed Doublets

    Navid Ardakanian

    Abelian flavor charges on right-handed fermions produce left-handed anarchy: we prove that all abelian discrete Froggatt-Nielsen models with uncharged left-handed doublets yield Haar-random PMNS and CKM matrices, regardless of ${\mathbb{Z}}_N$ group order, charge assignment, or Majorana mass structure. Scanning ${\mathbb{Z}}_3$ through ${\mathbb{Z}}_7$ with 12 charge assignments and $10^5$ Monte Carlo samples each, we demonstrate that the mass spectrum failure previously identified for ${\mathbb{Z}}_3$ -- the seesaw over-suppression mechanism that pushes $\Delta m_{21}^2/\Delta m_{31}^2$ to $\sim 10^{-11}$ -- is specific to ${\mathbb{Z}}_3$ and avoidable for $N\ge 4$. The mixing angle failure, however, is universal and irreducible. The PMNS angles from every abelian model are statistically consistent with Haar-random unitary matrices, with median ${\sin }^2{\theta }_{12}\approx {\sin }^2{\theta }_{23}\approx 0.50$ and ${\sin }^2{\theta }_{13}\approx 0.31$ across all models tested. The same applies to the CKM: the joint probability of achieving CKM-like mixing from generic $O(1)$ coefficients is $<2\times 10^{-6}$. We identify the algebraic origin of this obstruction: abelian groups have only one-dimensional representations, so each generation transforms as an independent singlet with 18 free parameters for three Dirac mass matrices -- far exceeding the 10 physical observables. The transition to non-abelian flavor symmetries such as $A_4$, whose triplet representation reduces free parameters to 4 at leading order, is required specifically for mixing structure. This obstruction applies to the well-motivated subclass of models where left-handed fields are uncharged; models that assign abelian charges to both left- and right-handed fields can evade it.

    hep-phhep-th1 citation
24. 24*

    Production of $K^{\ast }\Sigma$ and $D^{\ast }{\Sigma }_c$ in pion-induced reactions off the nucleon

    Sang-Ho Kim🇰🇷

    We investigate the mechanisms of strangeness production in the ${\pi }^{-}p\to K^{\ast 0}{\Sigma }^0$ and ${\pi }^{-}p\to K^{\ast +}{\Sigma }^{-}$ reactions within a hybrid Regge framework in which effective Lagrangian vertices are combined with Reggeized exchanges. The nonresonant background consists of $t$-channel $K$- and $K^{\ast }$-Reggeon exchanges, $s$-channel nucleon and $\Delta$ exchanges, and $u$-channel $\Sigma$- and $\Lambda$-Reggeon exchanges, whose roles differ markedly between the two isospin channels. We additionally include several $N^{\ast }$ and ${\Delta }^{\ast }$ resonances in the $s$ channel and find that the $\Delta (2150)1/2^{-}$ resonance provides the dominant near-threshold contribution. The resulting total and differential cross sections and spin-density matrix elements (SDMEs) are in good agreement with the available data. Additional measurements near threshold ($W\lesssim$ 2.5 GeV) would be valuable for clarifying the role of $s$-channel baryon resonances. Within the same framework, with Regge trajectories and energy-scale parameters fixed by a QGSM-motivated prescription, we also predict the cross sections for the charm-production reactions ${\pi }^{-}p\to D^{\ast -}{\Sigma }_c^{+}$ and ${\pi }^{-}p\to D^{\ast 0}{\Sigma }_c^0$. Their total cross sections are suppressed by approximately $4$--$5$ and $7$--$8$ orders of magnitude, respectively, compared with those of the corresponding strangeness-production reactions. These results may serve as useful guidance for future experiments at facilities such as J-PARC.

    hep-ph1 citation
25. 25*

    Uncover the correlation between jet energy correlators and multiplicity fluctuations

    Pi Duan🇨🇳 · Weiyao Ke🇨🇳 · Guang-You Qin🇨🇳 · Lei Wang🇨🇳

    The energy-energy correlator (EEC) and multiplicity are two fundamental observables probing complementary aspects of QCD jets: the former characterizes the angular structure of energy flows in a scale-dependent manner, while the latter is sensitive to the entire history of particle production. In this \emph{Letter}, we uncover a nontrivial correlation between them by studying the EEC as a function of jet internal multiplicity. We introduce the multiplicity-conditioned EEC jet function (MCJF) and perform a factorization calculation to next-to-leading order accuracy. It is found that, for jet samples selected at a given normalized multiplicity $\nu =N_{\mathrm{ch}}/⟨N_{\mathrm{ch}}⟩$, the EEC in the angular region ${\Lambda }_{\mathrm{QCD}}/p_{T,\mathrm{jet}}\ll \chi \ll R$ acquires a $\nu$-dependent anomalous dimension. Thus the $\nu$-conditioned EEC provides a direct and robust probe to the multiplicity generating function in the perturbative regime. In addition, understanding $\nu$ dependence of the EEC is also crucial for isolating possible multiplicity-dependent bias effects in the EEC measurements in nuclear environment.

    hep-phnucl-th3 citations
26. 26*

    Integrating out a heavy Higgs singlet: on the edge between SMEFT and HEFT

    Stefan Dittmaier🇩🇪 · Sebastian Schuhmacher🇩🇪 · Maximilian Stahlhofen🇩🇪

    We use a functional approach based on the background-field formalism and the expansion by regions to integrate out the heavy Higgs field (associated with the mass eigenstate H) at the one-loop level in a singlet extension of the SM, which features an additional real scalar singlet and a spontaneously broken $Z_2$ symmetry. We obtain an effective Lagrangian to $O(1/M_H^2)$ in the limit of large Higgs mass ($M_H\gg M_h=125$GeV) providing a consistent treatment of effects from Higgs mixing and the renormalization of the underlying model. The scaling behaviour of the model parameters in the large-$M_H$ limit determines whether the effective Lagrangian can be accommodated in the SM Effective Field Theory (SMEFT) or involves non-SMEFT operators within the more general Higgs Effective Field Theory (HEFT) framework. We choose a limit that ensures decoupling of beyond-SM (BSM) effects at $O(M_H^0)$ by demanding that the Higgs mixing angle $\alpha$ is of $O(M_h/M_H)$ and putting minimal constraints on the other input parameters. The considered model is restricted to massless fermions. Bottom-up (diagrammatic) matching with only bosonic SMEFT operators at $O(1/M_H^2)$ necessarily fails, although the BSM sector does not directly couple to massless fermions. However, it is possible to match SMEFT with bosonic and fermionic operators to the SESM in the considered large-$M_H$ limit. For the emerging Effective Field Theory (EFT) we give two alternative Lagrangians: one that includes only bosonic BSM EFT operators, but necessarily involves operators of non-SMEFT type, and another one that is of SMEFT form, but involves also fermionic EFT operators. We validate our results for the effective Lagrangians at NLO in the coupling expansion by verifying that the difference between EFT and full-theory predictions vanishes faster than $1/M_H^2$ for several electroweak observables in the large-$M_H$ limit.

    hep-phhep-th4 citations
27. 27*

    ${\Lambda }_{c}N$ correlation functions with leading-order covariant chiral interactions

    Ru-You Zheng🇨🇳 · Zhi-Wei Liu🇨🇳 · Li-Sheng Geng🇨🇳

    The ${\Lambda }_{c}p$ momentum correlation functions are investigated using ${\Lambda }_{c}N$ interactions derived within the covariant chiral effective field theory. Our analysis reveals that the interaction is weakly attractive in the spin-singlet ${}^1{S}_0$ channel. In contrast, the ${}^3{S}_1$ channel exhibits a pronounced sensitivity to coupled-channel effects, i.e., the inclusion of $S$--$D$ mixing results in a repulsive ${\Lambda }_{c}p$ interaction; its absence leads to a weakly attractive one. Consequently, the spin-averaged correlation function -- dominated by the triplet state weight -- exhibits repulsive behavior when the $S$-- $D$ mixing is present. Furthermore, the source size dependence of the correlation functions is examined, demonstrating that the resulting variations remain experimentally resolvable within the precision of current femtoscopic measurements. A systematic comparison with non-relativistic chiral effective field theory and phenomenological models yields distinct discrepancies in the femtoscopic correlation functions. These findings underscore the capacity of femtoscopy to discriminate between different theoretical descriptions of the ${\Lambda }_{c}N$ interaction and provide useful references for upcoming experimental data.

    hep-phhep-latPRD(2026)·1 citation
28. 28*

    Origin of the Covariant Wigner Operator as a Quantum Amplitude in QCD

    Chueng-Ryong Ji🇺🇸 · Daniel W. Piasecki🇺🇸

    The Wigner function plays a central role in QCD as a phase space object encoding correlations among quarks, antiquarks, and gluons, yet its interpretation remains subtle due to its quasiprobabilistic nature and possible negativity. Recent work based on the Koopman-von Neumann-Sudarshan (KvNS) Hilbert space formulation of classical mechanics suggests the Wigner function arises as a quantum probability amplitude projected onto classical phase space, rather than a quasiprobability density (Bondar et al., 2013; McCaul et al., 2023). In the classical limit, this amplitude reduces to the classical Koopman wavefunction. In this work, we extend this perspective to relativistic QCD by constructing a Koopman description of the quark Wigner operator. We show that the Wigner operator is naturally isomorphic to a phase space spinor, providing a unified framework in which both classical and quantum dynamics are expressed. Within this formulation, the Wigner function retains its interpretation as an amplitude even in the relativistic regime. This viewpoint clarifies the origin of negativity and other nonclassical features, and provides a more transparent foundation for parton distribution functions in QCD. Remarkably, the relativistic Koopman framework reproduces the classical limit of QCD.

    hep-phhep-thnucl-thSymmetry(2026)·1 citation
29. 29*

    Mechanical Equilibrium in the Magnetized Quark--Hadron Mixed Phase: A Covariant Generalization of the Gibbs Condition

    Aric Hackebill🇺🇸

    We formulate a covariant mechanical equilibrium condition for the quark-hadron mixed phase boundary in the presence of a magnetic-field-induced pressure anisotropy. Using the \emph{relativistic thin-shell} formalism to describe the quark-hadron boundary, we interpret conservation of stress-energy across the interface as a set of generalized Young--Laplace conditions which characterize the geometry of the interface. In a comoving stationary frame, this provides a covariant description of mechanical equilibrium at the interface, which serves as a replacement for the scalar pressure-balance condition used in the isotropic Gibbs construction.

    hep-phnucl-thUniverse(2026)·0 citations
30. 30*

    Quantum Fisher Information as a Probe of Sterile Neutrino New Physics:Geometric Advantage of KM3NeT over IceCube

    Baktiar Wasir Farooq🇮🇳 · Bipin Singh Koranga🇮🇳 · Aritro Chatterjee🇮🇳

    We investigate a reported discrepancy between a high-energy neutrino detection at KM3NeT and its non-observation at IceCube, which suggests a statistical tension of up to 3.5 standard deviations. This gap has been proposed to arise from sterile neutrino oscillations over the 147-kilometer path to KM3NeT, driven by either matter-induced resonances or nonstandard interactions. Using the Quantum Fisher Information framework, we quantify the sensitivity of the neutrino state to these new physics couplings and establish fundamental precision limits via the quantum Cramer-Rao bound. Our analysis shows that the information available at KM3NeT exceeds that at IceCube by three orders of magnitude for matter-induced scenarios. We demonstrate that IceCube would require over thirty times more events to match the precision of a single KM3NeT detection. We identify an optimal baseline of 150 to 200 kilometers, placing KM3NeT in a superior position for these measurements. Our results show that standard detection methods already reach the ultimate quantum precision limit, and that a small number of future events at KM3NeT could provide the first quantum-limited constraints on sterile neutrino couplings.

    hep-ph4 citations
31. 31*

    Lights, Camera, Axion: Tracing Axions from Supernovae in the Diffuse $\gamma$-ray Sky

    Brijesh Kanodia🇮🇳 · Debajit Bose🇮🇳 · Subhadip Bouri🇮🇳 · Ranjan Laha🇮🇳

    Axions produced copiously in core-collapse supernovae can convert into photons as they propagate through various astrophysical magnetic fields. The cumulative emission from the cosmic population of supernovae can therefore generate a diffuse gamma-ray signal through axion-photon conversion. In this work, we develop a comprehensive framework to compute the diffuse gamma-ray flux by modeling axion production in supernovae and, \textit{for the first time}, consistently accounting for their conversion into photons across all relevant magnetic field environments - progenitor, host galaxy, intergalactic medium, and the Milky Way - together with an updated cosmic star formation rate. Using measurements of the diffuse gamma-ray sky from COMPTEL, EGRET, and \textit{Fermi}-LAT, we derive competitive constraints on the axion-photon coupling over a wide range of axion masses. We further forecast the sensitivity of upcoming MeV gamma-ray telescopes to this diffuse signal using a Fisher forecast analysis.

    hep-phastro-ph.HEhep-ex1 citation
32. 32*

    Influence of tides and self-gravity on Ultra-Light Dark Matter Bounds from Dwarf Galaxies

    Andrea Caputo🇨🇭 · Luca Teodori🇮🇱

    Dwarf spheroidal galaxies provide some of the most sensitive astrophysical probes of ultra-light dark matter (ULDM), but the inferred constraints can be affected by two important systematics: tidal interactions with the Milky Way, which reduce ULDM-induced dynamical heating, and stellar self-gravity, which can become relevant if the stellar component was more compact at earlier times. In this work, we attempt to estimate both effects by reconstructing dwarf-galaxy orbital histories in a Milky-Way potential, adopting a simple and approximate tidal-susceptibility diagnostic that we argue provides a conservative description of tidal stripping, and explicitly including stellar self-gravity in our numerical simulations. Within our framework, which we apply to five different dwarf galaxies, we find that ULDM with masses $5\times 10^{-22}\lesssim m/\mathrm{eV}\lesssim 5\times 10^{-21}$ remains in tension with current data.

    hep-phastro-ph.COastro-ph.GAPRD(2026)·6 citations
33. 33*

    Reconciling hadronic and partonic analyticity in $b\to s\ell \ell$ transitions

    Martin Hoferichter🇨🇭 · Bastian Kubis🇩🇪 · Simon Mutke🇩🇪

    Rare $B$-meson decays mediated by $b\to s\ell \ell$ transitions constitute sensitive probes of physics beyond the Standard Model, and have triggered considerable interest due to hints for deviations from the Standard-Model prediction. To establish a discrepancy beyond a reasonable doubt, control over the nonlocal matrix elements involving charm loops is essential, which, for large spacelike virtualities, can be constrained by an operator product expansion with coefficients known at two-loop order. We observe that the analytic structure of this partonic calculation, whose understanding is important to put forward rigorous parameterizations, follows from simple triangle topologies and demonstrate explicitly how dispersion relations are fulfilled even in the case of anomalous thresholds. Crucially, these anomalous contributions match onto the ones expected when considering hadronic degrees of freedom, proving that the partonic calculation does not miss anomalous effects and justifying its use in regions of parameter space in which a perturbative description applies.

    hep-phhep-exnucl-thPLB(2026)·5 citations
34. 34*

    Non-Cold Dark Matter from Memory-Burdened Primordial Black Holes

    Valentin Thoss🇩🇪 · Laura Lopez-Honorez🇧🇪 · Florian Kühnel🇩🇪 · Marco Hufnagel🇧🇪

    Non-cold dark matter particles can arise from the evaporation of primordial black holes (PBHs). In this paper, we further investigate how the memory-burden effect, which delays the full evaporation of black holes, affects the Lyman-$\alpha$ bound on such non-cold dark matter (NCDM) particles. We mainly focus on scenarios in which PBHs have fully evaporated by today, undergoing a semi-classical evaporation phase followed by a memory-burden dominated phase. In this framework, PBH evaporation generically leads to two distinct dark-matter populations with different velocity dispersions, which can imprint observable signatures on the matter power spectrum. We compute the resulting NCDM phase-space distribution and its impact on small-scale overdensities using the $\text{BlackHawk}$ and $\text{CLASS}$ codes. This is then used to reinterpret Lyman-$\alpha$ forest constraints for thermal warm dark matter, deriving both a velocity-dispersion-based and a matter-power-spectrum-based estimate. In particular, we discuss how we obtain constraints on scenarios in which NCDM particles constitute only a fraction of the total relic dark matter. Finally, we discuss the viable parameter space as a function of dark matter masses, PBH initial conditions, and memory-burden parameters. We show that even subdominant NCDM components from PBH evaporation can be constrained, and confirm that NCDM can only account for all of the dark matter in the absence of PBH domination, as in the semi-classical case.

    ↳ astro-ph.COhep-phJCAP(2026)·3 citations
35. 35*

    A Solar Probe of Dark Matter Decay in the Galaxy

    Maximilian Detering🇬🇧 · Shyam Balaji🇬🇧

    Dark matter (DM) particles decaying in the Galactic halo can inject energetic $e^{\pm }$ that inverse-Compton scatter (ICS) solar photons into $\gamma$-rays, producing a diffuse and extended halo of emission around the Sun. We present the first quantitative study of this signal as an indirect probe of decaying DM. The intense solar photon field in the inner heliosphere amplifies the inverse-Compton emissivity by many orders of magnitude relative to the interstellar radiation field, making the Sun an unusually sensitive local converter of sunlight into $\gamma$-rays via scattering with injected $e^{\pm }$. Using 15 years of Fermi-LAT solar-halo data, we derive stringent limits on the DM lifetime for 10 GeV-10TeV masses at the level of ${\tau }_{\chi }\sim 10^{27}\mathrm{s}$ in leptonic decay channels. The predicted surface brightness rises steeply toward the Sun, and the $\gamma$-ray flux falls off at high energy due to Klein-Nishina suppression. Solar ICS $\gamma$-rays measured with degree scale angular resolution therefore provide a novel and complementary probe of DM decays, adding a local $\gamma$-ray search channel that is systematically distinct from both Galactic diffuse analyses and direct charged-particle measurements.

    ↳ astro-ph.HEhep-ph0 citations
36. 36*

    Generalized Predictions for the Electromagnetic Signatures of Mirror Stars

    Franco Cabral · Stuart Williamson · David Curtin🇨🇦 · Christopher D. Matzner🇨🇦

    Mirror Stars are a generic prediction of dissipative dark matter models, including minimal atomic dark matter and twin baryons in the Mirror Twin Higgs. Mirror Stars capture regular atoms from the interstellar medium through highly suppressed kinetic mixing interactions between the regular and the dark photon. This results in the accumulation of a "nugget", which draws heat from the mirror star core and emits distinctive X-ray and optical signals. In this work, we solve the stellar structure equations of optically thick nuggets across a wide range of the effective mirror star parameter space, and characterize their emission spectra using stellar atmosphere models. This complements an earlier analysis of lower-mass optically thin nuggets. We find that optically thick mirror star nuggets occupy distinct regions of the (stellar surface temperature, luminosity, surface gravity) space, and can be distinguished from regular stars in both HR diagrams and temperature-surface-gravity diagrams using astrometric and spectroscopic stellar catalogues. Our detailed predictions, which are publicly available, now give for the first time a general picture of mirror star signals in the optical and IR to enable realistic mirror star searches using existing catalogues and new telescope observations.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAastro-ph.SR+11 citation
37. 37*

    Scattering phase shift in quantum mechanics on quantum computers: non-Hermitian systems and imaginary-time simulations

    Peng Guo🇺🇸 · Paul LeVan🇺🇸 · Frank X. Lee🇺🇸 · Yong Zhao🇺🇸

    To overcome the fast oscillatory behavior of correlation functions for extracting scattering phase shift in real-time quantum simulations encountered in Ref.\cite{Guo:2026qkx}, we propose and test two solutions in the present work. One is to simulate Hermitian systems in imaginary time, the other is to simulate non-Hermitian systems in real time. We demonstrate that both approaches lead to the problem of non-unitary quantum evolution which can be solved by combining two quantum algorithms: block encoding and Hadamard test. The combined quantum algorithm does not require mid-circuit measurements or adjustment of the input parameters of the Hamiltonian, and can be easily implemented on quantum computers. Numerical tests on quantum simulators show that both approaches agree with exact solutions for a sufficiently long time before the signal is lost in statistical fluctuations. The results bode well for using non-Hermitian and imaginary-time simulations to circumvent oscillations inherent in real-time simulation of other quantum systems. In particular, the non-Hermitian approach shows a decisive advantage over the imaginary-time one on the number of required ancillary qubits, and hence is more practical to scale up.

    ↳ quant-phcond-mat.otherhep-lathep-ph+1APS Open Sci.(2026)·3 citations
38. 38*

    Proton isovector helicity PDF at NNLO and the twist-3 moment ${\tilde{d}}_2$ from lattice QCD at physical quark masses

    Xiang Gao🇺🇸 · Andrew D. Hanlon🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Hai-Tao Shu🇨🇳 · Fei Yao🇺🇸 · Rui Zhang🇺🇸 · Yong Zhao🇺🇸

    We present a lattice quantum chromodynamics calculation of the $x$-dependent isovector quark helicity parton distribution function (PDF) of the proton in the large momentum effective theory (LaMET) framework. Through operator product expansion (OPE) we also extract the ${\tilde{d}}_2$ moment of the twist-3 PDF $g_T(x)$ for the first time in the $\overline{\mathrm{MS}}$ scheme, which is proportional to the average color Lorentz force experienced by the quark in the proton. This calculation is performed on a lattice of spacing $a$ = 0.076 fm at physical quark masses. The quasi-PDF matrix elements are measured in proton states boosted to momenta $P_z=\{0,0.25,1.02,1.53\}$ GeV. We first extract the lowest few helicity PDF moments from the renormalization-group (RG) invariant ratios of the matrix elements with OPE. Combined with the matrix elements relevant for $g_T(x)$, we obtain ${\tilde{d}}_2^{u-d}(2\mathrm{GeV})=0.0024(46)$ at next-to-leading order in $\overline{\mathrm{MS}}$. Then, the helicity quasi-PDF matrix elements are renormalized in the hybrid scheme with linear renormalon resummation and Fourier transformed to the $x$-space after an asymptotic extrapolation. The quasi-PDF is perturbatively matched to the $\overline{\mathrm{MS}}$ PDF with RG and threshold resummations at next-to-leading power and next-to-next-to-leading logarithmic accuracies. After resummations, we determine the PDF in the region $x\in [0.25,0.75]$ with controlled systematic uncertainties. The end-point regions are then parameterized, combined with the LaMET prediction at moderate $x$, and fitted to the short-distance matrix elements in coordinate space.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2026)·5 citations
39. 39*

    100 years of spin: fundamental physics, dark matter, exotic interactions, and all that

    Dmitry Budker🇩🇪 · Tim Chupp🇺🇸 · Klaus Kirch🇨🇭 · W. Mike Snow🇺🇸

    For a century, spin has been an indispensable probe of the fundamental laws of nature. A reflection on the role of spin in shaping modern physics is presented, from the early days of quantum mechanics to the latest precision tests of the Standard Model. The significance of magnetic and electric dipole moments in testing CP and CPT symmetries is surveyed, along with the ongoing searches for exotic spin-dependent interactions that may reveal the nature of dark matter and its connection to spacetime geometry. Through these vignettes, it is shown that spin continues to provide a fresh perspective on the most profound questions in physics today.

    ↳ quant-phhep-ph0 citations
40. 40*

    Statistical Mechanics of Quarkyonic Matter

    Marcus Bluhm (SUBATECH, Nantes)🇫🇷 · Yuki Fujimoto (Niigata U. and Wako, RIKEN)🇯🇵 · Marlene Nahrgang (SUBATECH, Nantes)🇫🇷

    We extend the theoretical formulation of Quarkyonic Matter within the IdylliQ model framework proposed in [Y. Fujimoto et al., Phys. Rev. Lett. 132, 112701 (2024) [1]] for zero temperature to non-zero temperatures. To this end, we develop a consistent statistical mechanics and grand canonical ensemble description of Quarkyonic Matter as a quantum system subject to additional inequality constraints due to the Pauli exclusion principle acting simultaneously on baryons and their constituent quarks. These constraints result in a significant reduction in the number of physically available baryon states compared to an ideal Fermi gas. As a consequence, the one-particle baryon distribution function factorizes into a thermal Fermi-Dirac distribution and a momentum-dependent density of states. This separation allows us to derive a proper definition of the entropy density that satisfies the third law of thermodynamics in the zero-temperature limit. Moreover, we find that inside Quarkyonic Matter the physical temperature and the physical baryon chemical potential differ from the Lagrange multipliers appearing in the Fermi-Dirac distribution which may have important consequences for the thermodynamics of Quarkyonic Matter.

    ↳ nucl-thhep-phhep-th1 citation
41. 41*

    QCD in strong magnetic fields: fluctuations of conserved charges and equation of state

    Heng-Tong Ding🇨🇳 · Jin-Biao Gu🇨🇳 · Arpith Kumar🇨🇳 · Sheng-Tai Li🇨🇳

    We present continuum-estimated (2+1)-flavor lattice QCD results for second-order fluctuations of conserved charges and the leading-order equation of state in the presence of strong magnetic fields at nonzero baryon chemical potential, using the HISQ action at the physical pion mass. The baryon-electric charge correlation ${\chi }_{11}^{\mathrm{BQ}}$ exhibits striking sensitivity to the magnetic field: $R_{cp}$-like double ratios ${\chi }_{11}^{\mathrm{BQ}}/{\chi }_2^{\mathrm{Q}}$ and ${\chi }_{11}^{\mathrm{BQ}}/{\chi }_{11}^{\mathrm{QS}}$ reach enhancements of $\sim 2$ and $\sim 2.25$ at $eB\simeq 8M_{\pi }^2$ along the transition line, establishing ${\chi }_{11}^{\mathrm{BQ}}$ as a magnetometer of QCD. To bridge theoretical predictions and experimental observations, we construct HRG-based proxy observables and apply systematic kinematic cuts emulating STAR and ALICE detector acceptances, which retain $\sim 80\%$ of the lattice QCD magnetic sensitivity. Extending to the QCD equation of state under strangeness neutrality and isospin asymmetry, we determine the chemical potential ratio $q_1\equiv ({\mu }_{\mathrm{Q}}/{\mu }_{\mathrm{B}}{)}_{\mathrm{LO}}$ and the pressure coefficient $P_2$ for magnetic field strengths up to $eB\simeq 0.8{\mathrm{GeV}}^2\sim 45M_{\pi }^2$. The results reveal temperature-band crossings, hierarchy reversals, and non-monotonic structures driven by the nontrivial interplay between thermal and magnetic effects.

    ↳ hep-lathep-phnucl-exnucl-thPoS(2026)·0 citations
42. 42*

    Gravitational wave spectrum from first-order QCD phase transitions based on a parity doublet model

    Bikai Gao🇯🇵 · Jingdong Shao🇨🇳 · Hong Mao🇨🇳

    We investigate the gravitational wave spectrum from first-order QCD phase transitions using the parity doublet model at finite baryon chemical potential. The model incorporates the chiral invariant mass $m_0$, representing the portion of nucleon mass that persists even when chiral symmetry is restored. Within the model, we identify two first-order phase transition regions: the nuclear liquid--gas transition and the chiral phase transition. By solving the bounce equation and computing the Euclidean action $S_3/T$, we obtain the gravitational wave spectra from both transitions. The liquid--gas transition yields $\alpha \sim \mathcal{O}(1)$ and $\beta /H\sim \mathcal{O}(10)$--$\mathcal{O}(100)$ near the endpoint of the first-order line, producing signals with peak frequencies from the millihertz to the nanohertz band that can fit the existing data. In contrast, the chiral transition produces signals suppressed by approximately five orders of magnitude, well below the sensitivity of all current and planned detectors. These results connect the chiral invariant mass to the gravitational wave spectrum, offering a novel probe of the origin of nucleon mass through gravitational wave astronomy.

    ↳ nucl-thastro-ph.HEhep-phPRD(2026)·1 citation
43. 43*

    Absorption of 1$P$-wave heavy charmonium ${\chi }_{c1}(1P)$ in nuclei

    E. Ya. Paryev🇷🇺

    We study the inclusive heavy charmonium ${\chi }_{c1}(1P)$ photoproduction from nuclei near the kinematic threshold within the collision model, based on the nuclear spectral function, for incoherent direct photon--nucleon charmonium creation processes. The model accounts for the final ${\chi }_{c1}(1P)$ absorption in nuclear medium, target nucleon binding and Fermi motion. We calculate the absolute and relative excitation functions on ${}^{12}$C and ${}^{184}$W target nuclei at near-threshold photon beam energies of 8.25--16.0 GeV, the absolute momentum differential cross sections and ratios of them for its production off these target nuclei at laboratory polar angles of 0${}^{\circ }$--10${}^{\circ }$ and for photon energy of 13 GeV as well as the A-dependences of the transparency ratios for the ${\chi }_{c1}(1P)$ at photon energy of 13 GeV within the different scenarios for its absorption cross section in nuclei. We demonstrate that the absolute and relative observables considered reveal distinct sensitivity to these scenarios. Therefore, they might be useful for the determination of this cross section from the comparison of them with the experimental data from the future experiments at the upgraded up to 22 GeV CEBAF facility, which is of crucial importance in understanding of charmonium production and suppression in high-energy heavy--ion collisions in a search for the quark-gluon plasma.

    ↳ nucl-thhep-exhep-phnucl-exNPA(2026)·1 citation
44. 44*

    Triaxial shapes and the angular structure of nuclear three-body correlations

    Hadi Mehrabpour🇨🇳 · Giuliano Giacalone🇨🇭 · Matthew W. Luzum🇧🇷

    Relativistic nuclear collisions have emerged as a new tool for probing many-body correlations of nucleons in the ground states of atomic nuclei. Here, we investigate the connection between three-nucleon correlations inside nuclei and three-particle correlations measured in collider final states. We work within a classical rigid-rotor picture of the colliding ions, whereby correlations in the lab frame arise solely from the averaging over orientations of an intrinsic-frame nucleon density with a triaxial quadrupole deformation, characterized by Bohr parameters ${\beta }_2$ and $\gamma$. With a Gaussian Ansatz for the density, we derive the leading-order form of the resulting two- and three-body nucleon distributions and perform a detailed analysis of their harmonic structure. With this, we provide an analytical understanding of empirical results linking shape parameters to final-state observables, notably, the fact that the covariance of the squared elliptic flow ($v_2^2$) with the mean transverse momentum ($[p_T]$), as well as the skewness of $[p_T]$ fluctuations, are to leading order proportional to ${\beta }_2^3\cos (3\gamma )$. This elucidates the connection between three-nucleon densities, nuclear triaxiality, and three-particle correlations in high-energy nuclear collisions.

    ↳ nucl-thhep-exhep-phnucl-ex6 citations
45. 45*

    Topological defect induced phase separation in a holographic system

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

    We investigate the coupled dynamics of symmetry breaking and phase separation during quenches across the critical point in a first-order phase transition. Based on the Einstein-Maxwell-scalar theory, we construct a holographic superfluid model with ${\mathbb{Z}}_2$ symmetry. By introducing higher-order nonlinear terms $\lambda {\Psi }^4$ and $\tau {\Psi }^6$ into the scalar field potential, we realize a rich phase structure, which enables us to study the coupling effects between symmetry breaking and phase separation. Furthermore, by preparing initial conditions with well-defined spatial partitions, we discover a new triggering mechanism for the invasion phenomenon, namely that kinks serve as triggering sites for the phase separation process. This study reveals a novel coupling mechanism between topological defects and phase separation, enriches our understanding of nonequilibrium structure formation in strongly coupled systems.

    ↳ hep-thastro-ph.COgr-qchep-ph3 citations
46. 46*

    Off-shell Chiral Dynamics in the $\Lambda (1405)$ Resonance and $K^{-}p$ Femtoscopic Correlations

    Jia-Ming Xie🇨🇳 · Zhi-Wei Liu🇨🇳 · Jun-Xu Lu🇨🇳 · Haozhao Liang🇯🇵 · Li-Sheng Geng🇨🇳

    We present the first systematic investigation of the $S=-1$ meson--baryon interaction within a fully off-shell covariant unitarized chiral effective field theory framework up to next-to-leading order. In particular, we perform a detailed comparison with the widely used on-shell approximation. We find that the resulting scattering observables are very similar, thereby confirming the validity of key results obtained within the on-shell scheme. A notable advantage of the off-shell treatment, however, is the absence of unphysical left-hand cuts induced by the on-shell approximation. Employing the off-shell amplitudes, we compute the femtoscopic correlation functions for $K^{-}p$ and ${\pi }^{\pm }{\Sigma }^{\mp }$ pairs. The $K^{-}p$ correlation functions are found to be consistent with previously published results based on the on-shell approximation, with marginal differences attributed to slight variations in the descriptions of the scattering data. The ${\pi }^{\pm }{\Sigma }^{\mp }$ correlation functions are predicted for the first time, and are expected to provide valuable constraints on the nature of the $\Lambda (1405)$ resonance and the coupled-channel chiral dynamics of the $K^{-}p$ system.

    ↳ nucl-thhep-phPRD(2026)·3 citations
47. 47*

    Sensitivity study of ${\bar{K}}_1(1270)$ decay dynamics using four $D\to {\bar{K}}_1(1270)(\to \bar{K}\pi \pi )e^{+}\nu$ decay channels

    Ying'ao Tang🇨🇳 · Liang Sun🇨🇳 · Panting Ge🇨🇳 · Menghao Wang🇨🇳

    A sensitivity study for the measurement of ${\bar{K}}_1(1270)$ decay modes is performed using semileptonic $D$-meson decays. The BESIII experiment is taken as a case study, where a simultaneous analysis of ${\bar{K}}_1(1270)$ decays to the four thee-body final states $K^{-}{\pi }^{+}{\pi }^{-}$, $K^{-}{\pi }^{+}{\pi }^0$, $K_S^0{\pi }^{+}{\pi }^{-}$, and $K_S^0{\pi }^{-}{\pi }^0$ is presented and a model-independent determination of \mbox{$\mathcal{B}({\bar{K}}_1(1270)\to \bar{K}\pi \pi )$}, without requiring detailed knowledge of intermediate resonant contributions, is proposed.

    ↳ hep-exhep-phCPC(2026)·0 citations
48. 48*

    Stability analysis and double critical phenomenon in the Einstein-Maxwell-scalar theory

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

    We investigate the dynamical stability and phase transition behavior in a holographic superfluid model incorporating higher-order self-interaction terms $\lambda |\psi {|}^4$, $\tau |\psi {|}^6$, and a non-minimal coupling $h(\psi )=e^{\alpha |\psi {|}^2}$. Thermodynamic and dynamical stability analyzes show that the thermodynamic stability and dynamical stability of the system are consistent. Phase diagram analysis reveals rich critical and supercritical phenomena. For fixed $\lambda <0$ and $\alpha$, increasing $\tau$ shrinks the first-order phase transition region to a critical point and then enters the supercritical region. When varying $\alpha$, the system can exhibit no critical point and, most notably, a double critical phenomenon in which, as $\alpha$ increases, the system first enters the supercritical region and then re-enters the first-order phase transition region. This double critical phenomenon driven by a single parameter is reported for the first time in holographic superfluid models, revealing a complex nonmonotonic coupling effect between the non-minimal coupling and higher-order interaction terms.

    ↳ gr-qcastro-ph.COhep-phhep-th1 citation
49. 49*

    Nonlinear Lattice Framework for Inflation: Bridging stochastic inflation and the $\delta N$ formalism

    Pankaj Saha🇯🇵 · Yuichiro Tada🇯🇵 · Yuko Urakawa🇯🇵

    Understanding when inflationary perturbations become genuinely nonlinear near the horizon crossing requires methods that go beyond both linear perturbation theory and the gradient expansion. In this work, we introduce a nonlinear lattice framework for single-field inflation based on a shear-free, locally Friedmann-Lemaître-Robertson-Walker geometry. This approach captures inhomogeneous local expansion rates, curvature contributions to the local Friedmann equation, and proper-volume weighting at a fraction of the computational cost of full numerical relativity. We construct fully nonlinear $\delta N$ observables on uniform-density slices, together with other practical time-dependent estimators for the curvature perturbations. After validating the framework in a standard slow-roll regime, we apply it to Starobinsky's linear-potential model featuring an intermittent ultra-slow-roll (USR) phase and a sharp potential transition. During this non-attractor USR regime, the lattice captures the separation of curvature perturbation estimators, the growth and subsequent stabilisation of non-Gaussianity, and a transient weakening of the shear-free approximation when the inflaton velocity becomes very small. Our framework provides a practical intermediate approach between rigid background lattice simulations and full numerical relativity, offering a nonlinear bridge between lattice methods, the $\delta N$ formalism, and the stochastic inflation formalism as perturbations transition beyond the linear regime.

    ↳ gr-qchep-phJCAP(2026)·6 citations
50. 50*

    QCD Anderson transition at zero and non-zero external magnetic fields

    Robin Kehr🇩🇪 · Adeilton Dean Marques Valois🇪🇸 · Lorenz von Smekal🇩🇪

    The QCD Anderson transition is believed to be connected to both deconfinement and chiral crossovers. These crossovers are substantially affected when external magnetic fields ($B$) are present, most prominently, e.g., via magnetic catalysis and inverse magnetic catalysis. In this work, we use lattice QCD to investigate the Anderson transition in two different setups: (1) at $B=0$ by studying the low-lying eigenmodes of the overlap operator using gauge configurations with $2+1+1$ quark flavors of twisted-mass Wilson fermions. We estimate the mobility edge below which eigenmodes are localized via the inflection point of the so-called relative volume. Previous work has shown that, contrary to expectations, this estimate does not vanish at the temperature of the chiral phase transition. A possible scenario for this apparent contradiction was discussed, and in this work, we present an alternative observable for measuring localization that supports this scenario. And (2) by studying the localization properties of the staggered Dirac operator at $B\ne 0$ on configurations with $2+1$ dynamical staggered fermions and 2 stout-smearing steps. Our preliminary results on two lattice spacings ($24^3\times 6$ and $24^3\times 8$) indicate a non-monotonic behavior of the mobility edge with the magnetic field across different temperatures, which hints at a reduction in the Anderson transition temperature in the presence of an external magnetic field.

    ↳ hep-lathep-phPoS(2026)·0 citations
51. 51*

    Energy Correlators from Star Integrals via Mellin Space

    Anastasia Volovich🇺🇸 · Di Wu🇨🇳 · Kai Yan🇨🇳

    We explore the Mellin space representation for the collinear limit of $N$-point energy correlators in $\mathcal{N}=4$ super-Yang-Mills theory. We show that these correlators can be written as integro-differential operators acting on star integrals: one-loop $n$-gons in $n$ dimensions. For the three-point energy correlator, we obtain the Mellin representation, use it to relate the correlator to the massive box integral, and show how to solve this relation to match with the expected result. For the four-point energy correlator, we obtain the Mellin representation and use it to write the correlator to a sum of various box and hexagon integrals in special kinematics. Our results provide a systematic method to relate higher-point energy correlators in the collinear limit to star integrals, which are known exactly.

    ↳ hep-thhep-ph1 citation
52. 52*

    Curvature-induced electroweak symmetry breaking and phase transition of a Higgs-portal dark scalar field

    Andreas Mantziris🇵🇹

    This overview of the study arXiv:2407.18845, regarding the possibility of generating gravitational waves from a curvature-induced phase transition of a non-minimally coupled scalar dark matter field with a Higgs-portal, was showcased at the "Workshop on Standard Model and Beyond 2025" of the Corfu Summer Institute 2025. The phase transition dynamics during the transition from inflation to kination were calculated for various inflationary scales, considering both positive and negative values of the non-minimal coupling, while also examining the potential for triggering electroweak symmetry breaking. Notably, kination enhances the GW amplitudes, significantly restricting the viable parameter space. While the GW spectra follow the usual rule for high-frequencies from high inflationary scales, certain regions of the parameter space allow for a potential detection with future experiments.

    ↳ astro-ph.COgr-qchep-phhep-thPoS(2026)·0 citations
53. 53*

    Cosmology from asymptotically safe Proca theories

    Carlos Pastor-Marcos🇩🇪 · Lavinia Heisenberg🇩🇪 · Álvaro Pastor-Gutiérrez🇯🇵 · Jan M. Pawlowski🇩🇪 · Manuel Reichert🇬🇧

    Effective field theories for cosmology offer a powerful framework to investigate the dynamics of space--time and address longstanding open puzzles. In this work, we initiate a programme to analyse the ultraviolet completion of vector--tensor quantum field theories within the asymptotic safety paradigm, focusing on generalised Proca theories with a vector condensate. This enables us to assess whether a consistent fundamental UV completion exists and to constrain the set of viable infrared scenarios. Using the non--perturbative functional renormalisation group, we identify several fixed points, including Proca--type candidates, and, among them, a particularly remarkable one with four relevant directions: two associated with gravity and two induced by matter. This provides evidence for the non--perturbative renormalisability of vector--tensor theories. We further outline how the resulting UV critical surface constrains late--time cosmology.

    ↳ gr-qchep-phhep-th4 citations
54. 54*

    Approximate Energy-Integration Method for Identifying Collisional Neutrino Flavor Instabilities

    Jiabao Liu🇯🇵 · Hiroki Nagakura🇯🇵

    We present an approximate energy-integration method for identifying collisional neutrino flavor instabilities. Direct evaluation of the dispersion relation requires multi-dimensional integrals over neutrino phase space, making systematic searches for unstable modes in numerical models of core-collapse supernovae (CCSNe) and binary neutron star mergers (BNSMs) computationally expensive. In the literature there are some approximate schemes, but they are largely restricted to the homogeneous limit and can exhibit inaccuracies as reported in recent studies. In the current paper, we clarify the origin of the limitations in previous schemes and provide a better approximation method that robustly preserves the key physics of spectral asymmetries and collision rates. It yields a reduced dispersion relation that is inexpensive to evaluate. Comparison with exact solutions demonstrates that our new approximate method shows a good performance in computing both real frequencies and growth rates across a wide range of regimes, including isotropic and anisotropic neutrino distributions for both homogeneous and inhomogeneous modes. This provides a practical, accurate, and scalable framework for identifying collisional flavor instabilities in high-energy astrophysical simulations such as CCSNe and BNSMs.

    ↳ astro-ph.HEhep-phPRD(2026)·1 citation
55. 55*

    Infinite Heat Order in 3+1 Dimensions

    Borut Bajc🇸🇮 · Giulia Muco🇩🇰 · Francesco Sannino🇩🇰 · Sophie Wagner🇩🇰

    We investigate whether spontaneous symmetry breaking can persist up to arbitrarily high temperature in ultraviolet-complete quantum field theories in four spacetime dimensions. We focus on completely asymptotically free models with gauge group $\mathrm{SU}(N_{c1})\times \mathrm{SU}(N_{c2})$ and two complex scalar fields, each transforming in the fundamental representation of one gauge factor and singlet under the other. The scalar potential contains quartic self-interactions together with a negative portal coupling between the two sectors. In the Veneziano limit, this class of theories was previously shown to admit fixed-flow trajectories for which one scalar acquires a negative thermal mass at asymptotically large temperature, leading to symmetry non-restoration. Here we extend that analysis to finite numbers of colours and flavours. We derive the finite-$N$ fixed-flow equations, compute the leading $1/N$ corrections to the large-$N$ solutions, and solve the full finite-$N$ system numerically. We find explicit finite-$N$ benchmark theories for which the scalar potential remains bounded from below, the gauge sector is asymptotically free, and one scalar thermal mass stays negative at arbitrarily high temperature. This provides an explicit perturbative example of infinite heat order in a four-dimensional ultraviolet-complete quantum field theory with a finite field content.

    ↳ hep-thcond-mat.stat-mechhep-phPRD(2026)·2 citations
56. 56*

    Multimessenger Constraints on Production Sites of High-Energy Neutrinos from NGC 1068

    Abhishek Das🇺🇸 · Kohta Murase🇺🇸 · B. Theodore Zhang🇯🇵

    The detection of high-energy neutrino signals from the nearby Seyfert galaxy NGC 1068 provides us with a unique opportunity to explore nonthermal processes near the center of supermassive black holes. Using the IceCube and Fermi-LAT data, we present general multimessenger constraints on the energetics of cosmic rays and the compactness of the neutrino emission region ($\mathcal{R}$), considering not only $p\gamma$ but also $pp$ processes. Compared to the photohadronic scenario, the hadronuclear scenario can alleviate constraints on the emission region, yielding $\mathcal{R}\lesssim 30-70$ for low-$\beta$ plasma and $\mathcal{R}\lesssim 5-50$ for high-$\beta$ plasma. While our results support the previous conclusion that the photohadronic scenario favors a compact corona with $\mathcal{R}\sim 3-10$, these suggest the relevance of further investigations into $pp$ neutrino contributions. When the cosmic-ray spectrum is extended from 1 GeV, we find that the requred cosmic-ray luminosity exceeds the X-ray luminosity for a spectral index of $s_{\mathrm{CR}}\gtrsim 2$, which challenges some shock acceleration models. We also show that the beta decay scenario is unlikely even if the magnetic field is as strong as the maximum allowed by the Eddington luminosity. Given that NGC 1068 can be established as a neutrino source, our results will provide evidence for the standard hadronic scenario, including magnetically powered corona models having hard spectra with $s_{\mathrm{CR}}\lesssim 2$.

    ↳ astro-ph.HEastro-ph.GAhep-ph1 citation
57. 57*

    Three-form lifting of dilaton flat direction without and with gravity

    Georgios K. Karananas🇩🇪

    Spontaneous scale symmetry breaking is commonly associated with a flat direction in the action. We show that this need not be so if the dilaton is coupled to a three-form field in a manner compatible with gauge invariance and dilatations. The resulting effective dynamics lifts the flat direction without introducing explicit scale-violating operators. When gravity is included, the corresponding potential takes the form of an exponential plateau.

    ↳ hep-thgr-qchep-ph1 citation
58. 58*

    Descending into the Modular Bootstrap

    Nathan Benjamin🇺🇸 · A. Liam Fitzpatrick🇺🇸 · Wei Li🇺🇸 · Jesse Thaler🇺🇸

    In this paper, we attempt to explore the landscape of two-dimensional conformal field theories (2d CFTs) by efficiently searching for numerical solutions to the modular bootstrap equation using machine-learning-style optimization. The torus partition function of a 2d CFT is fixed by the spectrum of its primary operators and its chiral algebra, which we take to be the Virasoro algebra with $c>1$. We translate the requirement that this partition function is modular invariant into a loss function, which we then minimize to identify possible primary spectra. Our approach involves two technical innovations that facilitate finding reliable candidate CFTs. The first is a strategy to estimate the uncertainty associated with truncating the spectrum to the lowest dimension operators. The second is the use of a new singular-value-based optimizer (Sven) that is more effective than gradient descent at navigating the hierarchical structure of the loss landscape. We numerically construct candidate truncated CFT partition functions with central charges between 1 and $\frac{8}{7}$, a range devoid of known examples, and argue that these candidates likely come from a continuous space of modular bootstrap solutions. We also provide evidence for a more stringent constraint on the spectral gap near $c=1$ than the existing bound of ${\Delta }_{\mathrm{gap}}\le \frac{c}{6}+\frac{1}{3}$.

    ↳ hep-thcs.LGhep-phJHEP(2026)·7 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.