Tue·Mar 31, 2026Tuesday·March 31, 2026

1. 01*

   Axion EFT in the BMHV Scheme: Flavor Currents, Evanescent Operators and Ward Identities

   Deepanshu Bisht🇮🇳 · Sabyasachi Chakraborty🇮🇳 · Atanu Samanta🇮🇳

   We present a systematic analysis of axion effective field theory within the Breitenlohner-Maison-`t Hooft-Veltman (BMHV) scheme, focusing on the renormalization of fermionic dimension-five operators and the associated chiral flavor currents. In this framework, the non-anticommuting nature of ${\gamma }_5$ in $d\ne 4$ dimensions leads to violations of naive Ward identities through the emergence of evanescent operators. We derive the bare and renormalized Ward identities for chiral currents, explicitly identifying the equation-of-motion and evanescent operator contributions. Using diagrammatic calculations, we verify the validity of these identities up to two-loop order $\mathcal{O}({\alpha }_s^2)$, including both pole and finite terms. We demonstrate how evanescent operators mix into physical operators and determine the finite renormalization required to restore four-dimensional Ward identities, recovering the expected structure of axial current renormalization and the anomaly. Our results provide a consistent and transparent framework for multi-loop computations in axion EFT and highlight the essential role of evanescent operators in maintaining scheme consistency.

   hep-phhep-th2 citations
2. 02*

   Density screening effects in the NJL model: Chiral condensate, speed of sound, and the Critical End Point

   Alejandro Rosas Díaz🇲🇽 · Alfredo Raya🇲🇽 · C. A. Vaquera Araujo🇲🇽 · S. Hernández-Ortiz🇲🇽

   The phase diagram of Quantum Chromodynamics (QCD) remains a central topic in high-energy physics. At high temperature and low baryochemical potential, the chiral transition is experimentally observed and theoretically explored to be a smooth crossover, while at high densities, a first-order phase transition is theoretically expected in lack of direct experimental evidence. The search for the Critical End Point (CEP), where both regimes meet, is one of the main objectives of heavy-ion experiments at FAIR and NICA. In this work, we explore the QCD phase diagram structure using the Nambu--Jona-Lasinio (NJL) model, incorporating medium screening effects through an effective coupling $G(T,\mu )$ for $\mu \gg T\sim 0$. We apply a consistent regularization scheme and Sommerfeld expansion to include low thermal and large density corrections in the gap equation. Our numerical analysis focuses on the behavior of the chiral condensate, the dynamical quark mass, and the speed of sound. We find that screening effects shift the posible position of the CEP and modify the nature of the chiral transition. These findings provide theoretical support for ongoing experimental searches and may have implications for the physics of compact stars.

   hep-phhep-thnucl-th0 citations
3. 03*

   Signatures from pion condensation and lepton flavor asymmetries in the cosmological gravitational wave background

   Osvaldo Ferreira🇧🇷 · Eduardo S. Fraga🇧🇷 · Jürgen Schaffner-Bielich🇩🇪

   Large lepton flavor asymmetries at the QCD epoch could generate a pion condensation phase in the early Universe. For large enough tau lepton flavor asymmetries, the speed of sound can exceed the conformal value, leaving a distinctive imprint on the low-frequency gravitational wave (GW) spectrum from causal sources. Beyond probing the formation of a pion condensation phase, the detection or non-detection of this signature in future Pulsar Timing Arrays (PTAs) datasets would provide a novel constraint on lepton asymmetries in the early Universe. We determine the corresponding GW spectrum and its tilt, comparing them with the standard case of vanishing lepton asymmetry. Finally, we discuss the implications for the stochastic GW background reported by PTAs, using the NANOGrav 15-year dataset.

   hep-phastro-ph.COnucl-th2 citations
4. 04*

   Agentic Diagrammatica: Towards Autonomous Symbolic Computation in High Energy Physics

   Tony Menzo🇺🇸 · Alexander Roman🇺🇸 · George T. Fleming🇺🇸 · Sergei Gleyzer🇺🇸 · Konstantin T. Matchev🇺🇸 · Stephen Mrenna🇺🇸

   We present Diagrammatica, a symbolic computation extension to the HEPTAPOD agentic framework, which enables LLM agents to plan and execute multi-step theoretical calculations. Symbolic computation poses a distinctive reliability challenge for LLM agents, as correctness is governed by implicit mathematical conventions that are not encoded in a form that can be easily checked in the computational backend. We identify two complementary remedies, tool-constrained computation and targeted knowledge grounding, and pursue the first as the primary architecture. Concretely, we concentrate the agent's action distribution onto tool calls with convention-fixing semantics, in which the agent specifies a compact, human-auditable diagram specification and a trusted backend performs the symbolic or numerical manipulations exactly. The toolkit provides two complementary calculation paths consuming a shared diagram specification: Naive Dimensional Analysis (NDA) for order-of-magnitude rate estimates and Exact Diagrammatic Analysis (EDA) for tree-level symbolic calculations via automatic FeynCalc code generation, both supplemented by automatic Feynman diagram enumeration and a navigable theory knowledge base. The architecture is validated on two benchmarks: (1) an exhaustive catalog of all tree-level, single-vertex $1\to 2$ partial decay widths across scalar, fermion, and vector parents, with complete massless and threshold limits and Standard Model validation; and (2) an NDA sensitivity study of the muon decay multiplicity ${\mu }^{+}\to {\nu }_{\mu }{\bar{\nu }}_e+n(e^{+}{e}^{-})+e^{-}$, determining the maximum observable $n$ at current and planned muon experiments.

   hep-ph9 citations
5. 05*

   Layered dark structure with a Structuring Field: A $Z_4$-symmetric Inert Doublet-Singlet realization and implications for the $S_8$ tension

   Marriam Naeem🇵🇰 · Mohid Farhan🇵🇰

   We introduce the Layered Dark Sectors with a Structuring Field (LDS-SF), a structured cosmological framework where the internal architecture of a multi-component dark sector naturally generates scale-dependent growth of structure. In this framework, the characteristic scale dependence is derived from the dominant eigenvalue, $\lambda (k)$, of the dark sector's perturbation matrix. This structurally-driven mechanism modifies structure growth while preserving the standard $\Lambda$CDM background expansion and General Relativity. We provide a minimal realization of this framework within a two-component DM $Z_4$-symmetric Inert Doublet Singlet Model ($Z_4$-IDSM). By integrating out the heavy inert doublet mediator, we derive a contact-interaction Effective Field Theory (EFT) for a 60~GeV singlet dark matter candidate. This interaction manifests macroscopically as an effective sound speed $c_s^2$, which we map to the LDS-SF eigenmode evolution. We implement this system into the CLASS Boltzmann code, employing a late-time activation function that projects virialized halo properties into the linear perturbation framework. We also compute the relic density using micrOMEGAs to further stress-test the relic abundance predictions of viable parameters. Our numerical analysis demonstrates that while the model remains indistinguishable from $\Lambda$CDM at the era of recombination, it introduces a targeted suppression of the matter power spectrum at late times ($z<10$) and small scales ($k>0.1h/\text{Mpc}$). Confronting the model with Planck CMB, BAO, and growth-rate measurements, we find three instances of couplings that successfully alleviate the $S_8$ tension, bringing the predicted amplitude into $1\sigma$ agreement with weak-lensing data from KiDS-1000 and DES. This work establishes LDS-SF as a mathematically consistent and observationally viable extension of standard cosmology.

   hep-phastro-ph.COPhys.Scripta(2026)·2 citations
6. 06*

   Two-Loop Spacelike Splitting Amplitudes in Full-Color QCD

   Federico Buccioni🇩🇪 · Hanyu Fang🇨🇳 · Kai Yan🇨🇳

   The study of QCD scattering amplitudes in the collinear regime provides crucial insight into the factorization properties of hadronic cross sections. In this paper, we present the first complete results for two-loop spacelike splitting amplitudes in full-color QCD, in all partonic channels and helicity configurations. We confirm the universality of a class of contributions already found in N=4 super Yang--Mills (sYM) theory, and identify previously unknown sources of collinear factorization-violating (CFV) effects. Consistent with recent observations in N=4 sYM, all CFV contributions cancel in color-summed squared amplitudes, implying the universality of single-parton collinear factorization for jet cross sections at third order in QCD.

   hep-phhep-th5 citations
7. 07*

   Light and Heavy $Z^{\prime }$ from Flavored Chiral $U(1{)}_X$ Gauge Symmetries: Purely Axial and Mixed Vector-Axial Couplings

   Hemant Kumar Prajapati🇮🇳 · Rahul Srivastava🇮🇳

   Model independent phenomenological studies, ranging from neutrino to B-physics, often consider effective interactions involving either purely vector (V), purely axial vector (A), or mixed vector and axial vector (V, A) couplings. While pure vector $Z^{\prime }$ interactions can naturally emerge in gauged $U(1{)}_X$ extensions of the Standard Model, such as the $B-L$ model, generating other coupling structures from a UV complete theory is highly nontrivial. To realize such couplings, we propose a new class of flavor specific chiral $U(1{)}_X$ gauge symmetries. Gauge anomaly cancellation is achieved by introducing three right-handed neutrinos charged under the $U(1{)}_X$ symmetry. We systematically classify anomaly free charge assignments and analyze viable ultraviolet completions with minimal scalar content, requiring no additional fermions beyond the three necessary for anomaly cancellation. We present several benchmark models illustrating the range of possible charge assignments, under which the quark and lepton flavor structures can differ substantially, leading to distinct phenomenological signatures. In particular, such non universal charge configurations naturally give rise to $Z^{\prime }$ mediated flavor changing neutral currents in both the quark and lepton sectors. We also demonstrate that, within this framework, the $Z^{\prime }$ boson can naturally acquire purely axial vector or mixed vector-axial couplings to the SM fermions, both in the heavy and light $Z^{\prime }$ regimes.

   hep-ph5 citations
8. 08*

   Late-time attractors in relativistic spin hydrodynamics in Gubser flow

   Gen-Hui Li🇨🇳 · Xiang Ren🇨🇳 · Dong-Lin Wang🇨🇳 · Shi Pu🇨🇳

   We investigate the late-time asymptotic solutions and attractor structure of the spin density in minimal causal spin hydrodynamics in Gubser flow. After deriving the differential equation governing the spin density, we obtain its late-time asymptotic solutions and identify both attractors and repellers in the corresponding numerical solutions. We then map these solutions back to flat Minkowski space and find parameter regions where the spin density exhibits a power-law decay. We further show that, when the characteristic length scale of the system is much larger than the proper time, several components of the spin density can decay as slowly as conventional thermodynamic variables in relativistic hydrodynamics. In this regime, the spin density behaves as a hydrodynamic mode governed by the late-time scaling laws of the flow.

   hep-phhep-thnucl-th2 citations
9. 09*

   Chiral Phase Transition in Rotating Quark Matter with Chiral Imbalance: A Medium Separation Scheme Regularized NJL Model Study

   Huang-Jing Zheng🇨🇳 · Peng Nan🇨🇳 · Sheng-Qin Feng🇨🇳

   We investigate the chiral phase transition in rotating quark matter with chiral imbalance using the two-flavor Nambu-Jona-Lasinio (NJL) model regularized by the Medium Separation Scheme (MSS). Our numerical calculations demonstrate that the chiral chemical potential ${\mu }_5$ and angular velocity $\omega$ exert opposite effects on chiral symmetry breaking: ${\mu }_5$ enhances the breaking, raising the pseudocritical temperature $T_{pc}$ and sharpening the phase transition, while $\omega$ suppresses the breaking, lowering $T_{pc}$ and smearing the transition. Notably, chiral imbalance buffers the rotation-induced softening of the phase transition-the suppression of $T_{pc}$ by $\omega$ weakens progressively as ${\mu }_5$ increases. The MSS predicts a monotonic increase of $T_{pc}$ with ${\mu }_5$, in qualitative agreement with LQCD, resolving the discrepancy found in traditional regularization. Furthermore, the rotational suppression of $T_{pc}$ exhibits strong radius dependence: larger rotation radii amplify the suppression due to enhanced spacetime curvature and centrifugal effects, and can even induce an abrupt drop in $T_{pc}$ in the high-rotation region. These findings clarify the interplay between rotation and chiral imbalance in modulating the QCD chiral phase transition and validate the MSS as a reliable regularization framework for such extreme systems.

   hep-phEPJC(2026)·2 citations
10. 10*

    Particle-antiparticle perturbation superhorizon crossing: baryogenesis, leptogenesis, magnetogenesis and darkogenesis

    She-Sheng Xue🇮🇹

    During the reheating epoch, gravitationally produced superheavy particle-antiparticle pairs undergo quantum oscillations. Perturbations in their relative densities cross out the horizon, leading to an asymmetry of particles and antiparticles inside the horizon. Massive particles decay into light baryons and leptons, thereby explaining baryogenesis and leptogenesis, whose charged components must generate a nontrivial electric current, thereby producing a primordial magnetic field (magnetogenesis). As a result, the baryon (lepton) number-to-entropy ratio and the primordial magnetic field bound are consistent with observational data. We also discuss darkogenesis, the origin of dark matter and anti-dark matter asymmetry.

    hep-phastro-ph.CO0 citations
11. 11*

    Vorticity-induced modifications of chemical freeze-out in heavy-ion collisions

    Nandita Padhan🇮🇳 · Kshitish Kumar Pradhan🇮🇳 · Arghya Chatterjee🇮🇳 · Raghunath Sahoo🇮🇳

    We investigate the influence of global rotation on the chemical freeze-out parameters in ultra-relativistic heavy-ion collisions. Within the framework of the hadron resonance gas (HRG) model, the freeze-out parameters are determined using commonly employed freeze-out criteria, namely the fixed energy per particle and the scaled entropy density, extended here to include rotational effects. We find that the presence of rotation leads to a systematic shift of the chemical freeze-out curve toward lower temperatures in the $T\text{–}{\mu }_B$ phase diagram. The behavior of the electric charge and strangeness chemical potentials in the presence of rotation is also analyzed, providing the first systematic study of their rotational dependence within the HRG framework. Furthermore, we examine the impact of rotation on experimentally relevant observables, including hadron yield ratios and susceptibility ratios of conserved charges. Our results show that while particle yield ratios exhibit noticeable sensitivity to rotation, the conventional cumulant ratios remain comparatively less affected. This indicates that hadronic yield ratios may provide a more suitable observable for estimating the magnitude of rotational effects generated in heavy-ion collisions.

    hep-phhep-exhep-thnucl-ex+1PLB(2026)·3 citations
12. 12*

    UV-Complete Models for a Light Axial Gauge Boson

    Bhaskar Dutta🇺🇸 · Aparajitha Karthikeyan🇺🇸 · Rabindra N. Mohapatra🇺🇸

    We present new anomaly free gauge models where the gauge field only has axial vector couplings to both quarks and leptons. We use the left-right symmetric universal seesaw models as the basis for this construction with an extra $U(1{)}_a$ as the axial gauge group. We present three main versions of the model, denoted as models A, B and C (and their variations), with different properties depending on the way the gauge anomaly is canceled. We show how the models can accommodate small neutrino masses. The models allow for a new Dirac fermion coupled via the $U(1{)}_a$ gauge portal to the SM fields which can be the dark matter. The models A and its variation have the novel property that there is an upper limit on the $U(1{)}_a$ gauge coupling $g_a$, due to the fact that the standard model Higgs doublet shares the $U(1{)}_a$ quantum number. For models B and C, we discuss the phenomenological constraints on the gauge coupling $g_a$ and gauge boson mass $m_{\mathcal{A}}$ from current low energy observations where, unlike in models A, $g_a$ depends on $m_{\mathcal{A}}$ through a single vacuum expectation value.

    hep-ph2 citations
13. 13*

    Deconstructed Weak Isospin from a Symplectic Symmetry

    Alastair Gosnay🇬🇧 · David J Miller🇬🇧

    Understanding the origin of flavour hierarchies in the Standard Model remains an open problem, motivating extensions with non-trivial flavour symmetries. We unify deconstructed weak isospin $\mathrm{SU}(2{)}_{\mathrm{L}}^3$ into an $\mathrm{Sp}(6{)}_{\mathrm{L}}$ symmetry at a high scale $v_S$. The three generations of Standard Model (SM) left-handed doublets are unified into a single fundamental representation of $\mathrm{Sp}(6{)}_{\mathrm{L}}$. In addition to two BSM triplets from the breaking of $\mathrm{SU}(2{)}_{\mathrm{L}}^3$, the enlarged symmetry predicts six additional gauge bosons below the unification scale: three $\mathrm{SU}(2{)}_{\mathrm{L}}$ triplets and three singlets, which induce flavour transitions in both the quark and lepton sectors, even in the presence of mass-gauge alignment. We derive updated bounds on the intermediate breaking scale $v_{12}$ of $\mathrm{SU}(2{)}_{\mathrm{L}}^3$ in the presence of the unification scale $v_S$, mapping exclusions in the $(v_{12},r)$ parameter space with $r=v_S^2/v_{12}^2$. The most stringent constraints arise from precision flavour observables involving first- and second-generation transitions, including neutral meson mixing ($K^0-{\bar{K}}^0$, $D^0-{\bar{D}}^0$), $\mu \to 3e$ and $\mu \to e$ conversion in nuclei. These measurements probe scales well beyond direct collider reach and imply $v_{12}\gtrsim 550\mathrm{TeV}$ for small $r\approx 1$, while for $r\gtrsim 100$ the bound relaxes to $v_{12}\gtrsim 150\mathrm{TeV}$, recovering the limits of the $\mathrm{SU}(2{)}_{\mathrm{L}}^3$ model. Additionally we include projections from Mu3e and COMET-I and -II experiments which show promising further reach into the parameter space.

    hep-phJHEP(2026)·2 citations
14. 14*

    Probe charmonium-nucleon interactions in high energy proton-proton collisions

    Jiaxing Zhao🇩🇪 · Taesoo Song🇩🇪 · Joerg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪 · Pol Bernard Gossiaux🇫🇷 · Klaus Werner🇫🇷

    We investigate charmonium production and the charmonium-nucleon correlation function in pp collisions using the EPOS4+CATS framework. For the first time, the emission source of charmonium-proton pairs is dynamically generated and found to be non-Gaussian. This enables a femtoscopic extraction of the charmonium-proton interaction directly from experimental correlation functions. Both ground and excited charmonium states are included. We found that the excited states induce sizable uncertainties even negative in the observed prompt $J/\psi$-proton correlation through feed-down effects, reflecting their stronger interactions.

    hep-phnucl-th2 citations
15. 15*

    Isolation of photon-nuclear interaction backgrounds in the search for the chiral magnetic effect in relativistic heavy-ion collisions

    Jing Gu🇨🇳 · Jinhui Chen🇨🇳 · Jie Zhao🇨🇳

    The chiral magnetic effect (CME) in relativistic heavy-ion collisions originates from a chirality imbalance among quarks within metastable QCD vacuum domains and may be linked to $CP$ violation, which is believed to play a crucial role in the matter-antimatter asymmetry of the universe. Over the past two decades, extensive experimental efforts at RHIC and the LHC have been devoted to the search for evidence of the CME. Recent advances have greatly improved our understanding of background contributions that can mimic CME-like signals. In particular, analyses utilizing techniques designed to suppress flow-related backgrounds indicate that the CME signal at RHIC, if present, is small. To further investigate potential background sources, particularly those associated with strong electromagnetic fields, we estimate the contribution from coherent photon-nuclear interactions. These interactions are driven by intense electromagnetic fields produced in ultrarelativistic heavy-ion collisions, with cross sections that scale with the field strength. Notably, the polarization of the incident photons is aligned with the electric field, which is oriented along the impact parameter direction and perpendicular to the magnetic field. Consequently, such processes can generate charge-dependent correlations that mimic key features of the CME signal, yet originate from different physics mechanisms and are distinct from flow-induced backgrounds. In this study, we quantitatively assess the influence of these coherent photon-nuclear interactions on the precision measurement of the CME, aiming to improve the separation of the genuine CME signal from these background contributions.

    hep-phhep-exnucl-exnucl-thPRC(2026)·0 citations
16. 16*

    News from Extended Scalar Sectors

    Tania Robens🇭🇷

    In this proceeding contribution, I give a short overview on selected topics regarding extended scalar sector phenomenology. After a short overview on extended scalar sectors with light scalars at Higgs factories, I concentrate on the Inert Doublet model and recent studies exploring its discovery potential at lepton colliders.

    hep-phPoS(2026)·1 citation
17. 17*

    Magnetic moments of open bottom--charm molecular pentaquark octets

    Halil Mutuk🇹🇷 · Xian-Wei Kang🇨🇳

    We present a comprehensive theoretical investigation of the magnetic moments of open heavy-flavor molecular pentaquarks with quark compositions $b\bar{c}qqq$ and $c\bar{b}qqq$ (where $q=u,d,s$). Employing a molecular picture in which the pentaquarks are treated as S-wave bound states of a heavy baryon and a meson, we systematically construct the complete spin--flavor wavefunctions for the two distinct SU(3)${}_f$ octet representations, $8_{1f}$ and $8_{2f}$, arising from symmetric and antisymmetric light-diquark configurations, respectively. Within the framework of the constituent quark model, we calculate the magnetic moments of spin-parity configurations, $J^P={\frac{1}{2}}^{-}({\frac{1}{2}}^{+}\otimes 0^{-})$ and $J^P={\frac{1}{2}}^{-},{\frac{3}{2}}^{-}({\frac{1}{2}}^{+}\otimes 1^{-})$, for each member of the $b\bar{c}$ and $c\bar{b}$ octets. Our results reveal a striking hierarchy: in the $8_{2f}$ representation, the ${\frac{1}{2}}^{+}\otimes 0^{-}$ states exhibit near-universal magnetic moments ($\mu \approx -0.062{\mu }_N$ for $b\bar{c}qqq$ and $\mu \approx +0.362{\mu }_N$ for $c\bar{b}qqq$), as a direct consequence of the spin-singlet light-diquark that suppresses light-quark contributions. In contrast, the $8_{1f}$ representation shows a broad spectrum of values with frequent sign changes, reflecting the active role of the symmetric light-diquark. The clear differences between the $b\bar{c}$ and $c\bar{b}$ families demonstrate explicit heavy-quark flavor symmetry breaking in electromagnetic observables. These predictions provide a detailed set of electromagnetic benchmarks that can serve as discriminants for the internal flavor structure and spin configuration of future experimentally observed open heavy-flavor pentaquarks, offering valuable guidance for ongoing and future searches at facilities such as LHCb and Belle II.

    hep-phhep-exhep-latnucl-ex+1PLB(2026)·3 citations
18. 18*

    Absence of Quadratic-Order Sensitivity to Small Neutrino Mass Splittings in Disappearance Measurements

    Sanjeev Kumar Verma🇮🇳

    Neutrino disappearance measurements using binned reconstructed-energy spectra exhibit a regime in which small mass-squared splittings become unidentifiable at quadratic order when smooth spectral shape uncertainties are represented by profiled nuisance parameters in the fit. In the small-phase limit, the oscillation-induced modification of the detected spectrum is quadratic in the mass-squared splitting and produces a smooth deformation of the reconstructed-energy distribution. If the nuisance deformation functions used in the fit can reproduce this energy dependence across the fitted bins, the quadratic oscillation-induced distortion can be absorbed by the systematic deformation space and the profiled chi-squared remains unchanged at this order. Sensitivity to the mass-squared splitting then arises only from higher-order oscillation effects or from restrictions imposed on the allowed smooth spectral freedom.

    hep-ph0 citations
19. 19*

    Large Hadronic Effects in $B\to K^{\ast }\mu \mu$?

    Wolfgang Altmannshofer🇺🇸 · Samuel G. Christensen🇺🇸 · Peter Stangl🇩🇪

    Recent results from LHCb have confirmed the long-standing $P_5^{\prime }$ anomaly, an intriguing discrepancy in the angular distribution of the $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ decay that might be a sign of new physics. In addition, the new results hint at a non-zero value for $S_7$, another observable that characterizes the $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ angular distribution. We stress that a non-zero $S_7$ cannot be explained by heavy new physics but instead necessarily requires a sizable hadronic effect that introduces a strong phase. We argue that, under plausible assumptions, the hadronic effect is of the correct size to also explain $P_5^{\prime }$. The direct CP asymmetry in $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ emerges in principle as a clean probe of new physics in such a scenario. We show that a combined fit of hadronic parameters and Wilson coefficients retains sensitivity to new physics and we find strong bounds on imaginary parts of new physics Wilson coefficients.

    hep-ph6 citations
20. 20*

    Central multiplicity distributions in the multi-channel eikonal model

    E. G. S. Luna🇧🇷 · M. G. Ryskin🇷🇺

    The multiplicity distribution of charged particles produced in the central rapidity region ($|\eta |<2.5$) is calculated within the multi-channel eikonal model using the AGK cutting rules and compared with ATLAS data at $\sqrt{s}=7$ and 13 TeV. The effects of color reconnection and/or string percolation are discussed.

    hep-phhep-exhep-thPRD(2026)·0 citations
21. 21*

    Associated Higgs production in lepton-photon collisions at FCC-ee

    Pankaj Agrawal🇮🇳 · Biswajit Das🇮🇳 · Tousik Samui🇮🇳

    Following the HL-LHC era, proposed lepton colliders highlight the need to study various important Higgs boson production mechanisms to precisely probe the Standard Model Higgs sector. We propose a novel mechanism $e^{\pm }\gamma \to {\bar{\nu }}_e({\nu }_e)H{W}^{\pm }$, which can be useful to study Higgs boson properties. This channel is relatively free from the background and can be used to measure the Higgs boson properties, in particular $WWH$ coupling. We examine the viability of this production mechanism. We show that the process can be observed at the planned FCC-ee with the center-of-mass energy of 365 GeV. At the center-of-mass energy of 500 GeV, the process can be observed within a few months of the operation. We use an in-house Monte Carlo event generator that simultaneously incorporates the photon distribution and electron/positron distribution. Our work is also a step towards realistic simulations of lepton- and photon-initiated processes at lepton colliders.

    hep-ph0 citations
22. 22*

    Full energy fraction and angular dependence of medium-induced splittings in the large-$N_c$ limit

    Carlota Andres🇫🇷 · Fabio Dominguez🇪🇸

    Jets produced in relativistic heavy-ion collisions are modified by their interactions with the quark-gluon plasma (QGP), making jet substructure observables sensitive probes of QGP dynamics. A quantitative description of these modifications requires understanding how the medium affects elementary parton splittings with full dependence on both their energy fraction $z$ and splitting angle $\theta$, beyond the widely used soft emitted-gluon approximation. Here, we study medium-induced $1\to 2$ splittings double-differential in $z$ and $\theta$, with full resummation of multiple scatterings, and show that in the large-$N_c$ limit and under the harmonic oscillator (HO) approximation, all path integrals can be evaluated analytically for any splitting channel, providing a computationally efficient semi-analytical result. We also revisit the semi-hard approximation (SHA), extending it to include leading corrections in inverse powers of the partons energies, which we denote the improved semi-hard approximation (ISHA), and assess its validity through a comparison with the large-$N_c$-HO results. Our analysis shows that while the SHA is found to be unreliable across most of phase space, even for high-energy emitters, the ISHA provides a robust approximation for splittings where all partons are sufficiently energetic.

    hep-phnucl-th5 citations
23. 23*

    Study of neutrinophilic low-mass dark matter mediated by pseudoscalar

    Zhuo Zhang🇨🇳 · Lian-Bao Jia🇨🇳 · Reyes J.F. Eduardo🇨🇳

    In this work, we investigate a neutrinophilic low-mass dark matter model mediated by a pseudoscalar particle. Since dark matter lacks Standard Model gauge charges, new interactions are required to connect it to the visible sector. Traditional indirect detection searches for annihilation products, such as cosmic rays, become ineffective when the annihilation predominantly yields invisible neutrinos. In our model, the present-day annihilation cross section into neutrinos (manifesting as a neutrino line) falls below current indirect detection limits. We therefore constrain the model using complementary probes: the Lyman-$\alpha$ forest, high-energy astrophysical neutrinos from active galactic nuclei and supernovae, direct detection via nucleon and electron scattering, and invisible Higgs decays. These observables provide stringent and multifaceted constraints on neutrinophilic dark matter interactions in the low-mass regime. Our results indicate that searches for the neutrino line from dark matter annihilations, neutrino self-interactions from supernovae and collider signatures, and invisible Higgs decays offer critical tests for the model's parameter space.

    hep-phastro-ph.HE0 citations
24. 24*

    Implications of the muon anomalous magnetic moment in a Doublet Left-Right Symmetric Model

    M. Zeleny-Mora🇲🇽 · R. Gaitán-Lozano🇲🇽 · R. Martinez🇨🇴

    We compute the complete set of one-loop contributions to the muon anomalous magnetic moment, $a_{\mu }=(g-2{)}_{\mu }/2$, in the Doublet Left-Right Symmetric Model (DLRSM), based on the gauge group $SU(2{)}_L\otimes SU(2{)}_R\otimes U(1{)}_{B-L}$ with neutrino masses generated via the inverse seesaw (ISS) mechanism. We evaluate all four one-loop topologies VFF, SFF, FVV, and FSS arising from the extended gauge bosons ($W^{\prime }$, $Z^{\prime }$), the new scalar sector ($H_3^0$, $A_1^0$, $H_R^{\pm }$, $H_L^{\pm }$), and the heavy neutrino spectrum generated by the ISS mechanism, using the Casas--Ibarra parametrization to express the neutrino mixing in terms of physical observables. Imposing the experimental bound on $\Delta a_{\mu }$, we establish that $v_R\lesssim 1$ TeV is excluded, implying lower bounds $m_{W^{\prime }}\gtrsim 325$ GeV, $m_{Z^{\prime }}\gtrsim 385$ GeV, and $m_N\gtrsim 700$ GeV under the manifest left-right symmetry condition $g_R=g_L$. Relaxing this condition to $g_R\ne g_L$ strengthens the gauge boson bounds to $m_{W^{\prime }}\gtrsim 1625$ GeV and $m_{Z^{\prime }}\gtrsim 1650$ GeV.

    hep-ph0 citations
25. 25*

    On the predictivity of axion dark matter in the presence of Peccei-Quinn breaking

    Michael Zantedeschi🇮🇹

    It is shown that the post-inflationary quantum chromodynamics (QCD) axion need not lead to a unique one-parameter prediction for the dark matter abundance whenever small explicit Peccei-Quinn symmetry breaking becomes dynamically relevant before the QCD transition. Although strongly constrained by the strong CP bound, such breaking remains phenomenologically viable and introduces a mass scale $\mu$ that can control the early-time dynamics, as the QCD contribution to the axion mass is thermally suppressed at high temperatures. In this case, the axion string-wall network annihilates earlier, and the relic abundance is no longer primarily set by QCD dynamics alone, but instead depends on $\mu$, in addition to $f_a$, the axion decay constant. This effect overlaps with the parameter space relevant for QCD axion dark matter and, depending on ultraviolet parameters and initial conditions, can extend across it entirely.

    hep-phhep-thPhys.Dark Univ.(2026)·2 citations
26. 26*

    $f_0(980)$ production from $K\bar{K}$ coalescence in pp collisions at $\sqrt{s}=5.02$ TeV within UrQMD

    Phacharatouch Chaimongkon · Krittaporn Anukulkitch · Pornrad Srisawad🇹🇭 · Natthaphat Thongyoo · Sukanya Sombun · Ayut Limphirat🇹🇭 · Yu-Peng Yan🇹🇭

    We investigate the production of the scalar meson $f_0(980)$ in proton--proton collisions at $\sqrt{s}=5.02$~TeV using the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) transport model supplemented with a $K\bar{K}$ coalescence afterburner. After conservatively tuning the UrQMD string-fragmentation parameters, the model reproduces the bulk charged-kaon production in the low-to-intermediate transverse-momentum region, providing the kaon phase-space distribution used as input for the coalescence calculation. In the present implementation, both charged and neutral kaon--antikaon pairs are considered, and each accepted $K\bar{K}$ pair is assigned to the isoscalar $f_0(980)$ and isovector $a_0(980)$ channels with an equal Monte Carlo probability. Using the updated integration analysis, we find that $\Delta p=0.4$~GeV/$c$ gives the best directly simulated agreement with the ALICE $p_T$ spectrum and integrated yield, while a linear interpolation between the neighboring points at $\Delta p=0.3$ and $0.4$~GeV/$c$ yields an interpolated optimum of $\Delta p^{\ast }\approx 0.365$~GeV/$c$. Within this constrained hadronic coalescence framework, the measured $f_0(980)$ production is reasonably described, and the results are consistent with interpreting the $f_0(980)$ as a late-stage $K\bar{K}$ molecular configuration formed near kinetic freeze-out in small collision systems.

    hep-ph1 citation
27. 27*

    Phenomenology developments in UPC: $\gamma \gamma \to \gamma \gamma$ scattering

    Paweł Jucha🇵🇱 · Antoni Szczurek🇵🇱

    We discuss several possible extensions of present studies of $\gamma \gamma \to \gamma \gamma$ scattering in ultraperipheral heavy ion collisions. One of the possible extensions are studies for lower diphoton invariant masses (smaller transverse momenta). There new mechanisms may show up. This includes possible studies with future FOCAL and ALICE 3 detectors. So far only coherent $\gamma \gamma \to \gamma \gamma$ processes, when initial photons couple to nuclei, were sudied theoretically. Recently we proposed to study also inelastic processes, when initial photons couple to individual nucleons. Without special cuts the corresponding processes are of the order of 20 - 30 \%. A study to which extent the inelastic processes survive with the present cuts used for the $\gamma \gamma \to \gamma \gamma$ studies is an interesting question. They can be of interest by itself and dedicated studies are suggested. We calculate also cross section for associated neutron production. Deviation from our predictions could signal presence of the inelastic contribution. Finally we discuss production of single photons in UPC ($AA\to AA\gamma$). Corresponding cross sections for selected mechanisms are presented.

    hep-ph0 citations
28. 28*

    Missing energy signatures of inelastic magnetic dipole DM at NA64e

    Sergei N. Gninenko🇷🇺 · N. V. Krasnikov🇷🇺 · I. V. Voronchikhin🇷🇺 · D. V. Kirpichnikov🇷🇺

    Some extensions of the Standard Model consider inelastic dark matter (iDM) as an attractive candidate for sub-GeV DM of thermal origin that could be detected at modern accelerators. In the present paper, we calculate the production rate of iDM pairs ${\chi }_1{\bar{\chi }}_0$ interacting with the ordinary photon via dipole magnetic moment in the reaction of high-energy electron scattering on nuclei, $e^{-}N\to e^{-}N{\chi }_1{\bar{\chi }}_0$, in the NA64e experiment at the CERN SPS. We derive the projected sensitivity of NA64e to such particles assuming of $\simeq 10^{13}$ 100 GeV electrons on target. We also show, that incorporating heavy vector meson decays, ${\gamma }^{\ast }N\to NV(\to {\chi }_1{\bar{\chi }}_0)$, alongside bremsstrahlung-like emission of inelastic dark matter pairs, $e^{-}N\to e^{-}N{\gamma }^{\ast }(\to {\chi }_1{\bar{\chi }}_0)$, will allow NA64e to probe previously unexplored regions of the iDM parameter space, in particular for modest mass splittings, $\Delta \simeq 5\times 10^{-2}$, and relatively light masses, $m_{{\chi }_0}\lesssim 100\text{mbox}MeV$.

    hep-phPRD(2026)·3 citations
29. 29*

    Precise predictions for trilinear Higgs couplings and Higgs pair production in extended scalar sectors with anyH3 and anyHH

    Henning Bahl🇩🇪 · Johannes Braathen🇩🇪 · Martin Gabelmann🇩🇪 · Kateryna Radchenko🇪🇸 · Georg Weiglein🇩🇪

    A central objective of future collider experiments is to probe the structure of the Higgs potential, which requires access to trilinear scalar couplings, in particular the self-coupling of the observed Higgs boson. While this coupling is fixed in the Standard Model (SM), it can receive sizable modifications in many Beyond the SM (BSM) scenarios, often connected to solutions of open problems such as the origin of the matter-antimatter asymmetry of the Universe. In theories with extended scalar sectors, radiative corrections involving additional scalar states can significantly affect both the Higgs self-coupling and other trilinear scalar interactions, with important consequences for predictions of physical observables. Precise theoretical calculations are therefore essential for the interpretation of precision Higgs measurements and for identifying indirect signatures of new physics. This contribution presents the latest version of the public tool anyBSM, which provides automated calculations of all trilinear scalar couplings at full one-loop order in arbitrary renormalisable theories, including full momentum dependence and flexible renormalisation-scheme choices. In addition, the new module anyHH for di-Higgs production in gluon fusion is discussed in several exemplary BSM models, including scenarios with multiple resonances.

    hep-phEur.Phys.J.Plus(2026)·4 citations
30. 30*

    Exclusive Hadron Observables in Neutrino Induced $2p2h$ Multinucleon Knockout

    Vedantha Srinivas Kasturi🇨🇭 · Juan Nieves🇪🇸 · Federico Sánchez🇨🇭 · Joanna Ewa Sobczyk🇸🇪

    We explore the combined lepton and hadron kinematic observables from the exclusive Valencia $2p2h$ model. We present variables of interest which are available due to the exclusive kinematics and compare them with the democratically distributed outgoing nucleon kinematics as currently treated in neutrino event generators. We also show the effect of nuclear re-scattering based on the NEUT semi classical cascade. We comment on the observability of these variables in current and future long baseline neutrino detectors.

    hep-phhep-exPRD(2026)·3 citations
31. 31*

    Blocking Mesogenesis

    Chaja Baruch🇮🇱 · Gilly Elor🇺🇸 · Jared M. Goldberg🇮🇱 · Omer Shtaif🇮🇱 · Yotam Soreq🇮🇱

    Mechanisms of Mesogenesis generate the baryon asymmetry and dark matter of the Universe through late-time decays of Standard Model mesons into baryons and dark matter states. Utilizing the CP violation in the meson systems themselves, the resulting baryon asymmetry is directly controlled by collider observables, the CP asymmetry $A_{CP}$, and the branching fraction for the meson decays. Experimental probes of these decays place strong constraints on the amount of $CP$ violation required, placing it well above observed limits in meson mixing. Additionally, strong lower bounds on the proton lifetime seemingly rule out Mesogenesis mechanisms which use $D$ mesons. In this work, we propose to circumvent these constraints by ``morphing'' the mass of the dark sector particles using a late-time phase transition. The change in mass of the final decay products kinematically excludes meson and proton decays, relaxing the constraints on the model parameter space.

    hep-phhep-exPRD(2026)·2 citations
32. 32*

    Combined analysis of the data on cross sections and spin density matrix elements for $K^{\ast }\Sigma$ photoproduction reactions

    Ai-Chao Wang🇨🇳 · Neng-Chang Wei🇨🇳 · Fei Huang🇨🇳

    In our earlier work [Phys. Rev. C \textbf{98}, 045209 (2018)], we analyzed the differential cross-section data from the CLAS Collaboration for the reactions $\gamma p\to K^{\ast +}{\Sigma }^0$ and $\gamma p\to K^{\ast 0}{\Sigma }^{+}$ using an effective Lagrangian approach. We found that a satisfactory description of the data required the inclusion of the $s$-channel $\Delta (1905)5/2^{+}$ resonance, in addition to $t$-channel exchanges of $K$, $\kappa$, and $K^{\ast }$, $s$-channel contributions from nucleons ($N$) and $\Delta$, $u$-channel exchanges of $\Lambda$, $\Sigma$, and ${\Sigma }^{\ast }$, and a generalized contact term. In the present work, we extend our analysis to incorporate the data on spin density matrix elements from the LEPS Collaboration for the $\gamma p\to K^{\ast 0}{\Sigma }^{+}$ reaction at photon energies $E_{\gamma }=1.85$--$2.96$ GeV. Our goal is to impose more stringent constraints on the theoretical model and obtain a more reliable understanding of the reaction mechanisms. We obtain two fits that describe the experimental data equally well. In both fits, the $\Delta (1905)5/2^{+}$ resonance plays an important role. However, the contribution from $t$-channel $\kappa$ exchange is significant in one fit but negligible in the other. This finding contradicts earlier claims in the literature that the LEPS parity spin asymmetry $P_{\sigma }$ data support a dominant role of $\kappa$ exchange in $\gamma p\to K^{\ast 0}{\Sigma }^{+}$. We also present predictions for $P_{\sigma }$ at $E_{\gamma }=8.5$ GeV, which may help clarify whether $\kappa$ exchange is indeed dominant in this reaction.

    hep-phnucl-thPRC(2026)·1 citation
33. 33*

    The force of attraction between nucleons due to vacuum fluctuation

    Anupam Ghosh🇮🇳

    We investigate quantum vacuum interactions arising from the zero-point fluctuations of a spatially confined massive scalar field. Deriving analytical expressions for the planar interaction energy and vacuum pressure, we identify a fundamental transition from the canonical power-law scaling of massless fields to a distinct quantum saturation regime. We prove that in the macroscopic limit, where the boundary separation far exceeds the field's Compton wavelength ($a\gg {\lambda }_c$), the interaction energy does not vanish; instead, it asymptotes to a persistent constant, $-\hslash c/(24\pi {\lambda }_c^3)$. This reveals a cohesive zero-point energy reservoir inherent to massive vacua. Applying this formalism to the femtometer scale of the deuteron (${}^2$H) nuclei, we demonstrate that confining massive pion fluctuations generates an attractive force between nucleons.

    hep-phhep-thnucl-thquant-ph0 citations
34. 34*

    Heavy-Flavor Fragmentation from HF-NRevo: Status, Prospects, and Intrinsic Charm

    Francesco Giovanni Celiberto🇪🇸 · Francesca Lonigro🇪🇸

    We report on recent developments of the Heavy-Flavor Non-Relativistic evolution (HF-NRevo) scheme, a framework designed to describe heavy-hadron formation through leading-power fragmentation at moderate and large transverse momentum. The approach combines short-distance inputs obtained from next-to-leading-order NRQCD calculations with collinear scale evolution in a variable-flavor-number scheme, ensuring a consistent treatment of heavy-flavor thresholds and partonic hierarchies. Within this setup we have constructed the NRFF1.0 family of fragmentation functions for $S$-wave heavy quarkonia in their leading NRQCD Fock states. We discuss prospective applications of the HF-NRevo framework in the heavy-ion environment, where it can provide a perturbative baseline for investigating medium-induced modifications of heavy-flavor fragmentation. Its explicit treatment of partonic channels and heavy-flavor thresholds makes it particularly suitable for exploring jet-quenching sensitivity, energy-loss mechanisms, and the emergence of medium-modified fragmentation patterns in the quark-gluon plasma. The HF-NRevo scheme has also been extended to the exotic sector through the TQ4Q1.x and newly released TQ4Q2.0 fragmentation sets, which describe the formation of fully heavy tetraquarks in multiple quantum configurations. These developments open a novel pathway to study quarkoniumlike states and to probe the intrinsic charm content of the proton in forward hadron-collision environments. Altogether, this program broadens the phenomenological reach of heavy-flavor fragmentation studies at the HL-LHC and future collider facilities, opening access to previously unexplored aspects of QCD and potential portals to New Physics.

    hep-phhep-exhep-thnucl-ex+1PoS(2026)·5 citations
35. 35*

    Bag Parameters for Heavy Meson Lifetimes

    Matthew Black🇬🇧 · Robert V. Harlander🇩🇪 · Jonas T. Kohnen🇩🇪 · Fabian Lange🇨🇭 · Antonio Rago🇩🇰 · Andrea Shindler🇩🇪 · Oliver Witzel🇩🇪

    We calculate the dimension-six $\Delta Q=0$ four-quark matrix elements describing heavy-meson lifetime ratios using the gradient flow with its short flow-time expansion as a renormalization procedure. On six RBC/UKQCD 2+1-flavor domain-wall fermion ensembles, we determine flowed bag parameters for physical charm and strange quarks and match to the $\overline{\text{MS}}$ scheme with perturbative short flow-time expansion coefficients through next-to-next-to-leading order (NNLO). A multi-scale matching procedure using renormalization-group running improves the extrapolation to zero flow time. For the operators relevant to $\tau (D_s)/\tau (D^0)$ at the SU(3)${}_{\mathrm{F}}$ symmetric point, we obtain $B_1^{\overline{\text{MS}}}(3\mathrm{GeV})=1.0524(97)$,$B_2^{\overline{\text{MS}}}(3\mathrm{GeV})=0.9621(70)$, ${ϵ}_1^{\overline{\text{MS}}}(3\mathrm{GeV})=-0.2275(76)$, and ${ϵ}_2^{\overline{\text{MS}}}(3\mathrm{GeV})=-0.0005(8)$ using a specific choice of evanescent operators. This is the first lattice-QCD determination of $\Delta Q=0$ four-quark operators with a full error budget. It opens the path towards higher-precision predictions of heavy-meson lifetimes and similar quantities exhibiting operator mixing under renormalization.

    hep-phhep-exhep-lat8 citations
36. 36*

    Removing the Cosmological Bound on the Axion Scale via Confinement During Inflation

    Gia Dvali🇩🇪 · Sophia Fitz🇩🇪 · Lucy Komisel🇩🇪

    We implement the scenario of early relaxation of the axion via a high scale confinement within $SU(5)$ grand unified theory and study an epoch of strong QCD in inflationary cosmology. We consider scenarios in which, during inflation, the $SU(5)$ is either entirely or partially in the confining phase. This generates an early potential for the axion and dilutes its energy density removing any cosmological upper bound on the decay constant. We show that a phase of strong QCD can be realized by at least two mechanisms: 1) A direct coupling between the inflaton and the gauge fields and/or 2) by restoration of the $SU(5)$ symmetry during the inflationary epoch. In the latter case, strong coupling is already achieved via the RG running of the $SU(5)$ gauge coupling. We show that the mechanism works for all known realizations of the invisible axion idea: Peccei-Quinn (PQ) type formulations in which the anomalous global symmetry is realized via additional scalars (DFSZ) or heavy fermions (KSVZ) as well as the two-form gauge axion formulation based entirely on the QCD gauge redundancy without any anomalous global symmetry. Even if the expectation value of the PQ scalar vanishes during inflation, the axion is a well defined degree of freedom represented by the phase of the fermion 't Hooft determinant. For the DFSZ case, this phase is composed out of a condensate of the ordinary quarks, amounting to an early universe version of the ${\eta }^{\prime }$-meson. In all considered scenarios, the present day axion can be a viable dark matter candidate for an arbitrarily large value of the decay constant.

    hep-phastro-ph.COastro-ph.HEhep-th7 citations
37. 37*

    Structure-dependent radiative corrections to $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ in the GVMD approach

    Carlo M. Carloni Calame🇮🇹 · Marco Ghilardi🇮🇹 · Andrea Gurgone🇮🇹 · Guido Montagna🇮🇹 · Mauro Moretti🇮🇹 · Oreste Nicrosini🇮🇹 · Fulvio Piccinini🇮🇹 · Francesco P. Ucci🇮🇹

    We compute the radiative corrections to the process of two-pion production in association with a hard photon in $e^{+}{e}^{-}$ annihilation by taking into account the non-perturbative structure of the pion in the one-loop calculation. For this purpose, we adopt the generalised vector meson dominance model to insert the pion form factor in loop integrals for the treatment of final-state radiation and initial-final state interference at next-to-leading order. We compare our predictions with the results of the naive factorised scalar QED approach for experimentally relevant observables in the measurement of the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ process. The computation extends previous results obtained for the energy scan process $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ and can be used to quantify the uncertainty due to the model describing the pion-photon interaction in radiative return experiments at flavour factories.

    hep-phhep-exPLB(2026)·6 citations
38. 38*

    The $B^{(\ast )}{\bar{K}}^{(\ast )}$-coupled-channel system in the hidden-gauge approach

    J. Sánchez-Illana🇪🇸 · R. Molina🇪🇸 · Pan-Pan Shi🇪🇸

    In this work we provide predictions for bottom-strange molecular states within the Hidden Gauge Formalism. We study the coupled-channel scattering of $B^{(\ast )}{\bar{K}}^{(\ast )}$ states and, by fixing only one free parameter to obtain the mass of a new excited $B_s^0$ state seen by the LHCb, we predict the pole parameters of six states in this sector. Concretely, we get that the masses of the flavor partners of the $D_{s0}(2317)$ and $D_{s1}(2460)$ states in the bottom sector are $5760$ and $5802$ MeV for the $B\bar{K}$ ($J^P=0^{+}$) and $B^{\ast }\bar{K}$ ($1^{+}$) states, respectively. Moreover, the recently seen states by the LHCb with masses around $6100$ and $6160$ MeV can be interpreted as $B{\bar{K}}^{\ast }$ and $B^{\ast }{\bar{K}}^{\ast }$ molecular states, according to reasonable values of the pole parameters and the splitting between these two states obtained in our calculation.

    hep-phPLB(2026)·1 citation
39. 39*

    Hadron spectra and thermodynamics for all quark flavors from a universal Hagedorn temperature

    Michał Marczenko🇵🇱 · Larry McLerran🇺🇸 · Krzysztof Redlich🇵🇱

    We show that hadrons in QCD follow a spectrum determined by string dynamics characterized by a universal Hagedorn temperature linked to the string tension. While this behavior was recently established for light hadrons and glueballs, we demonstrate that the same dynamics describes the heavy-flavor sector. After separating the current quark masses, the resulting spectrum reproduces lattice QCD thermodynamics of charmed hadrons and the observed spectra of hadrons across quark flavors without additional parameters. These results reflect the universal confining dynamics of QCD through the string tension.

    hep-phnucl-th1 citation
40. 40*

    Charge-Dependent Directed Flow in Symmetric Nuclear Collisions

    Vipul Bairathi🇨🇱 · Kishora Nayak🇮🇳

    The directed flow ($v_1$) of identified hadrons (${\pi }^{\pm },K^{\pm },p,\bar{p},\varphi ,\Lambda$, and $\bar{\Lambda }$) is studied in symmetric nuclear collisions (O+O, Cu+Cu, Ru+Ru, Au+Au, and U+U) at $\sqrt{s_{NN}}=200$ GeV using the string-melting version of a multiphase transport model with improved quark coalescence. The mid-rapidity $v_1$-slope ($d{v}_1/dy$) and its charge-dependent splitting ($\Delta d{v}_1/dy$) between particles and anti-particles are investigated as a function of nuclear mass number ($A$) and collision centrality in both low-$p_{\mathrm{T}}$ (0.2$-$2.0 GeV/$c$) and high-$p_{\mathrm{T}}$ (2.0$-$5.0 GeV/$c$) regions. At low-$p_{\mathrm{T}}$, the $v_1$-slope shows weak system-size dependence, while at high-$p_{\mathrm{T}}$ strong system-size dependence is found and it becomes negative with nuclear mass number, reflecting the hard-soft asymmetry in particle production. The charge-dependent splitting $\Delta d{v}_1/dy$ reveals a striking baryon-meson dichotomy: baryon pairs ($p-\bar{p}$ and $\Lambda -\bar{\Lambda }$) exhibit significant splitting that grows with system size, whereas meson pairs (${\pi }^{+}-{\pi }^{-}$ and $K^{+}-K^{-}$) show minimal splitting. The effect of final state hadronic interactions on the $v_1$-slope is found to be negligible confirming that it is primarily generated during the partonic phase and coalescence process. A comparison of the AMPT results with measurements from the STAR experiment at RHIC in Au+Au collisions establish the transported quark contribution as a baseline for the observed charge-dependent $v_1$ splitting, on top of which electromagnetic field effects must be considered.

    hep-phnucl-thJ.Phys.G(2026)·0 citations
41. 41*

    Determining $G$ with Laser Spectroscopy to 38 ppb

    Noah Bray-Ali🇨🇦

    A precision measurement is proposed to determine, in a couple hours of integration time, the axion Compton frequency using a modest power (3 mW) tunable external-cavity diode laser at 2458 nm as input to drive a free-space table-top Mach-Zehnder interferometer whose sensing arm passes the expanded beam-waist ($3\mathrm{mm}$) light beam through a $1\mathrm{T}$ strong, $40\mathrm{cm}$ long dipole magnetic field created by a custom-built permanent-magnet assembly with a large but achievable ($6\mathrm{mm}$) gap between poles. As the laser frequency is slowly modulated at 1 kHz through a 65 MHz wide window that is well within the 30 GHz fine-tuning range of the laser, a small but readily observable modulation appears in the dark-port optical power of the dark-fringe phase-locked interferometer due to photons converting into axions within the light beam as it passes through the magnetic field. Measuring the axion Compton frequency, ${\nu }_A\approx 122\mathrm{THz}$, where the dark-port power modulation peaks, to within the line-width of the laser, $\Delta {\nu }_A=1\mathrm{MHz}$, then determines $G$ to 38 ppb, a roughly 600-fold improvement, through a relation between ${\nu }_A$ and $G$, involving $h$, $c$, and nucleon masses.

    hep-phphysics.optics0 citations
42. 42*

    Gauge couplings of the Standard Model in the octonionic framework: invariant normalisations, a conditional weak-sector completion, and a scale-explicit matching ledger

    Tejinder P. Singh🇮🇳

    We present a major revision of the gauge-sector account of the $E_8\otimes E_8$ octonionic unification programme. Exact identities within the specified algebraic construction, consequences of an effective support model, and microscopic hypotheses are kept separate. The recurrent 3/8 is the squared half-spacing of the adopted exceptional-Jordan family spectrum, while the exponential charge dependence is a multiplicative-character hypothesis motivated by the trace-dynamics action; the action parameter ${\alpha }_{\mathrm{TD}}$ is not the fine-structure constant. On the real ladder space $H_6$, the real Schur lemma fixes the shape of a colour-singlet self-adjoint photon profile to be proportional to the identity; the resulting 1/6 dilution holds only if the Hilbert-Schmidt norm coincides with the norm induced by the projected gauge kinetic term. This gives the conditional boundary value $[{\alpha }_{\gamma }^{(0)}{]}^{-1}=137.04006064$, while comparison with CODATA requires the calculable factor $Z_{\gamma }=1.0000296379$. We also repair the two-U(1) matter-current normalisation: for parent charges $c_{1}Y$, $c_{2}Y$ with $c_1+c_2=1$, a link field leaves the diagonal connection coupled to exactly the Standard-Model $Y$. Equal connection coefficients and zero kinetic mixing give the illustrative benchmark $g_Y^2/g_2^2=3/10$, ${\sin }^2{\theta }_W=3/13$; trace-induced normalisation of the scaled generators gives a different result, so 3/13 is not an embedding-independent prediction; treated as exact, it lies about $13\sigma$ below the quoted $\overline{\mathrm{MS}}$ value. The colour bound ${\alpha }_s/{\alpha }_{\mathrm{em}}\le 8$ is restricted to colour profiles individually commuting with the complex structure. Measured couplings enter only as inputs to scale and running diagnostics. The result is a falsifiable conditional programme and a normalization audit, not a parameter-free derivation of Standard-Model gauge couplings.

    hep-ph2 citations
43. 43*

    Rotation of the polarization plane in axion fields: application to neutron star polar cap regions

    Iver H. Brevik🇳🇴 · Moshe M. Chaichian🇫🇮 · Tiberiu Harko · Yuri N. Obukhov

    We study observable manifestations of an axion field, focusing on possible polarizational effects for electromagnetic wave propagating in such a special magnetoelectric medium. The corresponding analysis is based on a geometric model of the Casimir type, in the framework of which the rotation angle of the polarization plane is derived to the lowest order. The results obtained are discussed for astrophysical conditions of a neutron star, where an existence of a locally inhomogeneous axion region is predicted in the polar cap.

    hep-phastro-ph.HEhep-th0 citations
44. 44*

    Entanglement Signatures of CPT Violation in Neutrino Oscillations

    Bipin Singh Koranga🇮🇳 · Baktiar Wasir Farooq🇮🇳

    We investigate the joint influence of CPT violation and quantum-gravity-induced Planck-scale corrections on the entanglement entropy of two-flavor neutrino oscillations. Building on the CPT-violating neutrino mass matrix arising from flavour-blind Planck-scale physics, we compute the von Neumann entanglement entropy separately for neutrinos and anti-neutrinos and demonstrate that CPT violation directly imprints an observable asymmetry in their entropy profiles. For a degenerate mass spectrum (m_{\nu}\simeq2\,\mathrm{eV}), non-zero Majorana phases a_{1} and a_{2} are required to reproduce the solar KamLAND discrepancy; these same phases control the amplitude of the entropy asymmetry. Our results establish that entanglement entropy provides a sensitive and novel probe of CPT-violating Planck-scale physics within neutrino phenomenology.

    hep-ph2 citations
45. 45*

    Boltzmann Equation Solver for Thermalization

    Jong-Hyun Yoon🇰🇷

    We present BEST (Boltzmann Equation Solver for Thermalization), a Python framework for solving the momentum-resolved Boltzmann equation for arbitrary $n_{\mathrm{in}}\to n_{\mathrm{out}}$ scattering processes. The collision integral is evaluated directly in $3(n_{\mathrm{total}}-2)$ dimensions using the VEGAS adaptive Monte Carlo algorithm with vectorized batch evaluation. Momentum conservation is enforced exactly by expressing one particle's momentum through the constraint, while energy conservation is imposed via a narrow Gaussian representation of the delta function. We identify a subtlety in the construction of the collision integral for processes with unequal initial and final multiplicities ($n_{\mathrm{in}}\ne n_{\mathrm{out}}$) involving identical particles: the full collision rate requires separate evaluation with the observed momentum pinned to each side of the reaction, weighted by the respective particle multiplicities. Failure to account for this leads to systematic violation of energy conservation. The code supports massive particles with time-dependent masses, Bose-Einstein and Fermi-Dirac quantum statistics, multiple coupled species, cosmological expansion with comoving momenta, and both Euler and Heun time integration. Parallelization is achieved by distributing independent momentum grid points across MPI ranks, yielding near-linear scaling to hundreds of cores. We validate the Monte Carlo results against a semi-analytical $2\to 2$ collision integral with exact energy conservation, following the phase-space reduction of Ala-Mattinen et al. As a demonstration, we study thermalization of a massive scalar field through a $2\leftrightarrow 3$ number-changing process and show that energy conservation is restored only when all identical-particle contributions are correctly summed. The code is publicly available at https://github.com/best-hep/best.

    hep-phastro-ph.COphysics.comp-phComput.Phys.Commun.(2026)·5 citations
46. 46*

    Quasi-linear theory of fast flavor instabilities in homogeneous environments

    Damiano F. G. Fiorillo🇮🇹 · Georg G. Raffelt🇩🇪

    Dense neutrino plasmas can develop instabilities that drive collisionless flavor exchange, equivalent to the emission of flavomons, the quanta of flavor waves. We treat these waves, for the first time, as independent linear degrees of freedom and develop a quasi-linear theory (QLT), including backreaction on the neutrino distribution and nonresonant neutrino--flavomon interactions, while neglecting wave--wave processes. In a homogeneous, axisymmetric model, the saturated neutrino and flavomon distributions agree closely with periodic-box solutions of the original quantum kinetic equation. These results support the use of QLT, well established in plasma physics, to bypass nonlinear small-scale effects that challenge direct simulations.

    hep-phastro-ph.COastro-ph.HE6 citations
47. 47*

    Neutrinos as Dark Matter

    James M. Cline🇨🇦 · Gonzalo Herrera🇺🇸 · Jean-Samuel Roux🇨🇦

    Active neutrinos in standard cosmology were ruled out as a dark matter candidate in the 1980's. The reason is twofold: they are too light to account for the observed energy density of dark matter in the Universe, and their relativistic nature would spoil structure formation. In this note we suggest that an enhanced density of cold Standard Model active neutrinos today could behave effectively as dark matter, avoiding constraints from recombination and structure formation. Such an enhancement could be produced, for instance, by late-time decays of a light scalar field that is not in thermal equilibrium with the plasma. This mechanism is testable through the detection of the Cosmic Neutrino Background (C$\nu$B), which could have an average cosmological energy density a factor of $\sim 100-200$ times larger than expected in $\Lambda$CDM. The postulated light neutrinophilic scalar field may be observable, with Yukawa couplings in the range $y\sim 5\times 10^{-16}-10^{-12}$. A scenario preferred by structure formation constraints is that the scalar is a Majoron, and the neutrinos have an inverted mass hierarchy.

    hep-phastro-ph.COastro-ph.HE5 citations
48. 48*

    A Determination of the Top Mass from a Global PDF Analysis

    Richard D. Ball🇬🇧 · Jaco ter Hoeve🇬🇧 · Roy Stegeman🇬🇧

    We present an indirect determination of the top-quark pole mass $m_t$ within a global analysis of parton distribution functions (PDFs), based on the public NNPDF framework. We consider a wide range of measurements, including both single- and double-differential observables, computed at NNLO QCD accuracy with EW corrections, and analyse their individual as well as combined impact on the joint $({\alpha }_s,m_t)$ parameter space, while accounting for PDF evolution up to approximate ${\mathrm{N}}^3\mathrm{LO}$ QCD accuracy with QED corrections. We account for missing higher order QCD uncertainties by default. Unique to our analysis are the inclusion of, first, toponium contributions around the $t\bar{t}$ threshold, second, state-of-the-art constraints on ${\alpha }_s$ from the lattice, and finally, a detailed sensitivity study of the various ATLAS and CMS differential cross-section measurements at 8 and 13 TeV. We demonstrate explicitly how a combined determination requires the refitting of the PDFs in order to correctly correlate uncertainties. We find $m_t=172.80\pm 0.26$ GeV at approximate N${}^3$LO QCD including NLO QED, EW and toponium corrections.

    hep-phhep-exJHEP(2026)·3 citations
49. 49*

    Higgs Boson Spookiness: Probing Quantum Nonlocality with Spacetime-Resolved $H\to {\tau }^{+}{\tau }^{-}$ Decays

    Lawrence Lee🇺🇸 · John Lawless🇺🇸 · Caroline Riggall🇺🇸

    We demonstrate that a future precision $ee$ Higgs factory would be able to perform a spacetime-resolved test of quantum nonlocality in Higgs boson decays. In simulated $ee\to ZH\to (\mu \mu )(\tau \tau )$ events at $\sqrt{s}=240$ GeV, we reconstruct $\tau$ lepton decay vertices and measure spin correlations as a function of the spacetime interval between the two $\tau$ decays. Such a measurement would be able to test Bell-inequality-violating correlations for spacelike-separated decays, enabling direct exclusion of superluminal, finite-speed entanglement signaling theories. With 0.75 ab${}^{-1}$ of integrated luminosity, entanglement signal propagation speeds below $\approx 2c$ can be excluded at 95$\%$ CL. Signals establishing any spin correlation can be excluded for speeds below $\approx 9c$. This constitutes the first proposed spacetime-resolved measurement of electroweak quantum entanglement at a particle collider and demonstrates a unique capability of future Higgs factories.

    hep-phhep-exquant-ph2 citations
50. 50*

    Cherenkov plasmons emission by primordial neutrinos

    Maxim Dvornikov (IZMIRAN)🇷🇺

    We study the emission of Cherenkov plasmons by the gas of neutrinos with a nonzero temperature and a chemical potential. The background plasma, consisting of charged leptons, is taken to be nonrelativistic. The energy emission rate is obtained for longitudinal plasmons. To get the neutrino emissivity we average quantum field theory matrix element over the distribution functions of incoming and outgoing particles. Our results are applied for the description of the cooling down of a neutrino cluster formed in the early universe. Such clusters can exist owing to the neutrino interaction with a hypothetical light scalar boson. Using particular cluster parameters, we demonstrate that the considered cooling mechanism is efficient for some clusters. We find the temperature range where the proposed cooling channel is valid. Some useful calculations of the polarization tensor, as well as the plasmon form factors and their dispersion relations are also provided.

    hep-phastro-ph.COastro-ph.HEphysics.plasm-ph0 citations
51. 51*

    The connection between a classical vibrating drumhead and the masses of glueballs

    Thales Azevedo🇧🇷 · Henrique Boschi-Filho🇧🇷

    The powerful techniques of holographic quantum chromodynamics (QCD) can be employed in the investigation of glueballs -- composite particles made solely of gluons, the strong nuclear force mediators. In particular, the so-called hardwall model yields predictions for the values of the masses of various glueball states, which are related to the solutions of the differential equations of the model. It turns out that those equations are essentially the same as the ones governing the vibrations of a circular membrane like that of a drumhead, which may serve as extra motivation for studying the dynamics of such an object as an undergraduate physics student.

    ↳ hep-thhep-phphysics.ed-ph0 citations
52. 52*

    Derivation of the Schrodinger equation from fundamental principles

    Wenzhuo Zhang🇺🇸 · Anatoly Svidzinsky

    Schrodinger path to the quantum mechanical wave equation was heuristic and guided more by physical intuition than formal deduction. Here we derive the Schrodinger equation for the particle wave function, assuming that it has a meaning of the probability amplitude to find the particle at time t at point r and the relations E=hw, p=hk expressing particle energy and momentum in terms of the frequency and wave vector of the associated probability wave.

    ↳ quant-phhep-phhep-thphysics.hist-phEncyclopedia 6(2), 41 (2026)·1 citation
53. 53*

    PRBench: End-to-end Paper Reproduction in Physics Research

    Shi Qiu🇨🇳 · Junyi Deng🇨🇳 · Yiwei Deng🇨🇳 · Haoran Dong · Jieyu Fu · Mao Li · Zeyu Li🇨🇳 · Zhaolong Zhang🇨🇳 · Huiwen Zheng · Leidong Bao🇨🇳 · Anqi Lv · Zihan Mo and 39 other authors

    AI agents powered by large language models exhibit strong reasoning and problem-solving capabilities, enabling them to assist scientific research tasks such as formula derivation and code generation. However, whether these agents can reliably perform end-to-end reproduction from real scientific papers remains an open question. We introduce PRBench, a benchmark of 30 expert-curated tasks spanning 11 subfields of physics. Each task requires an agent to comprehend the methodology of a published paper, implement the corresponding algorithms from scratch, and produce quantitative results matching the original publication. Agents are provided only with the task instruction and paper content, and operate in a sandboxed execution environment. All tasks are contributed by domain experts from over 20 research groups at the School of Physics, Peking University, each grounded in a real published paper and validated through end-to-end reproduction with verified ground-truth results and detailed scoring rubrics. Using an agentified assessment pipeline, we evaluate a set of coding agents on PRBench and analyze their capabilities across key dimensions of scientific reasoning and execution. The best-performing agent, OpenAI Codex powered by GPT-5.3-Codex, achieves a mean overall score of 34%. All agents exhibit a zero end-to-end callback success rate, with particularly poor performance in data accuracy and code correctness. We further identify systematic failure modes, including errors in formula implementation, inability to debug numerical simulations, and fabrication of output data. Overall, PRBench provides a rigorous benchmark for evaluating progress toward autonomous scientific research.

    ↳ cs.CLhep-lathep-phphysics.comp-ph+16 citations
54. 54*

    Symbolic Density Estimation: A Decompositional Approach

    Angelo Rajendram🇨🇦 · Xieting Chu🇺🇸 · Vijay Ganesh🇺🇸 · Max Fieg🇺🇸 · Aishik Ghosh🇺🇸

    We introduce AI-Kolmogorov, a novel framework for Symbolic Density Estimation (SymDE). Symbolic regression (SR) has been effectively used to produce interpretable models in standard regression settings but its applicability to density estimation tasks has largely been unexplored. To address the SymDE task we introduce a multi-stage pipeline: (i) problem decomposition through clustering and/or probabilistic graphical model structure learning; (ii) nonparametric density estimation; (iii) support estimation; and finally (iv) SR on the density estimate. We demonstrate the efficacy of AI-Kolmogorov on synthetic mixture models, multivariate normal distributions, and three exotic distributions, two of which are motivated by applications in high-energy physics. We show that AI-Kolmogorov can discover underlying distributions or otherwise provide valuable insight into the mathematical expressions describing them.

    ↳ cs.LGhep-ph0 citations
55. 55*

    Observation of ${\Lambda }_c^{+}\to n{\pi }^{+}\eta$ and search for ${\Lambda }_c^{+}\to n{a}_0(980{)}^{+}$

    BESIII Collaboration: M. Ablikim · M. N. Achasov · P. Adlarson · X. C. Ai · C. S. Akondi · R. Aliberti · A. Amoroso · Q. An · Y. H. An · Y. Bai · O. Bakina · Y. Ban and 734 other authors

    By analysing 6.1 ${\mathrm{fb}}^{-1}$ of data collected at center-of-mass energies between $\sqrt{s}=4.600$ and 4.843 $\mathrm{GeV}$ with the BESIII detector at the BEPCII collider, we observe the decay ${\Lambda }_c^{+}\to n{\pi }^{+}\eta$ for the first time with a statistical significance of $9.5\sigma$. The ratio of branching fractions $\mathcal{B}({\Lambda }_c^{+}\to n{\pi }^{+}\eta )/\mathcal{B}({\Lambda }_c^{+}\to \Lambda {\pi }^{+}\eta )$ is measured to be $0.155\pm 0.031_{stat.}\pm 0.012_{syst.}$ Taking the world average of $\mathcal{B}({\Lambda }_c^{+}\to \Lambda {\pi }^{+}\eta )$ as reference, the absolute branching fraction is calculated to be $\mathcal{B}({\Lambda }_c^{+}\to n{\pi }^{+}\eta )=(2.94\pm 0.59_{stat.}\pm 0.23_{syst.}\pm 0.13_{ref.})\times 10^{-3}$. The intermediate process ${\Lambda }_c^{+}\to n{a}_0(980{)}^{+}$ is also searched for in the ${\pi }^{+}\eta$ invariant mass spectrum. Since no significant signal is found, the upper limit on $\mathcal{B}({\Lambda }_c^{+}\to n{a}_0(980{)}^{+})\times \mathcal{B}(a_0(980{)}^{+}\to {\pi }^{+}\eta )$ is set to $8.4\times 10^{-4}$ at 90\% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification.

    ↳ hep-exhep-phJHEP(2026)·2 citations
56. 56*

    Physics as Code: From Scans to Theorems with ITP APIs in $SU(5)$ Model Building

    Sven Krippendorf🇬🇧 · Joseph Tooby-Smith🇬🇧

    A recurring challenge in theoretical physics is to make reliable global statements about bounded but combinatorially large model spaces. Exhaustive scans quickly become opaque or impractical, while statistical exploration does not by itself provide theorem-backed guarantees. This motivates workflows in which the model-building problem itself is formalized inside an interactive theorem prover (ITP). In this paper we develop an API-based methodology for formalizing such bounded model-building questions inside Lean, an interactive theorem prover. The central step is to represent the relevant charge spectra, predicates, and reduction moves as reusable ITP definitions, and then to derive the classification from proved reduction theorems rather than from an ad hoc scan. We demonstrate the strategy in a concrete $SU(5)$ case study motivated by F-theory model building with additional Abelian symmetries. At the charge-spectrum layer, we classify bounded spectra that admit a top-quark Yukawa coupling, avoid a selected set of dangerous operators, and satisfy a minimal charge-spectrum completeness condition. Our main result shows that every such spectrum in the bounded search space arises from finitely many minimal top-Yukawa witnesses together with controlled completions and certified closure steps. This classification represents a formally verified description of the full viable class in the charge-spectrum setting studied here. The development is implemented inside PhysLib as reusable infrastructure rather than as a one-off verification script. It provides a proof of principle for how interactive theorem provers can turn combinatorially difficult model-building problems into correctness-first, reusable workflows, and we discuss how the resulting certified classification can serve as reliable input for downstream analyses.

    ↳ hep-thcs.LOhep-ph2 citations
57. 57*

    Heavy-Meson Bag Parameters using Gradient Flow

    Matthew Black🇬🇧 · Robert V. Harlander🇩🇪 · Jonas T. Kohnen🇩🇪 · Fabian Lange🇨🇭 · Antonio Rago🇩🇰 · Andrea Shindler🇩🇪 · Oliver Witzel🇩🇪

    We demonstrate the use of the gradient flow combined with the short flow-time expansion (GF+SFTX) as a renormalization procedure for four-quark operator matrix elements and associated bag parameters relevant to neutral heavy-meson mixing ($\Delta Q=2$) and heavy-meson lifetimes ($\Delta Q=0$). Using six RBC/UKQCD 2+1-flavor domain-wall fermion ensembles, we calculate for a charm-strange system with physical quark masses flowed bag parameters and match them to the $\overline{\text{MS}}$ scheme using perturbative SFTX coefficients up to next-to-next-to-leading order in QCD. We employ a multi-scale matching strategy and a renormalization-group improved flow-time evolution which allows for a reliable estimate of systematic uncertainties. For a fictitious neutral $D_s$ meson, we obtain the $\Delta Q=2$ $\overline{\text{MS}}$ bag parameter ${\mathcal{B}}_1^{\overline{\text{MS}}}(3\mathrm{GeV})=0.7673(123)$, consistent with existing short-distance $D^0$ mixing determinations. For the $\Delta Q=0$ lifetime-ratio operator basis, we find the $\overline{\text{MS}}$ results $B_1^{\overline{\text{MS}}}(3\mathrm{GeV})=1.0524(97)$, $B_2^{\overline{\text{MS}}}(3\mathrm{GeV})=0.9621(71)$, ${ϵ}_1^{\overline{\text{MS}}}(3\mathrm{GeV})=-0.2275(76)$, and ${ϵ}_2^{\overline{\text{MS}}}(3\mathrm{GeV})=-0.0005(8)$. We provide conversion formulae to re-express these results for an arbitrary choice of evanescent operators. These results demonstrate that GF+SFTX can deliver precise determinations of dimension-six four-quark operators and establish a framework for future lattice computations including more complex operator bases, where the challenge of power-divergent mixing is shifted to the continuum and handled in the SFTX.

    ↳ hep-lathep-exhep-ph7 citations
58. 58*

    Quantized Dissipation from the Inverse-Square Anomaly in a Non-Hermitian Klein-Gordon Field

    Mansour Haghighat🇮🇷 · Ali Nouri🇮🇷

    We construct an exactly solvable relativistic model that embeds the anomalous inverse-square interaction into a non-Hermitian Klein-Gordon field theory through a purely imaginary, scale-invariant scalar potential. The stationary field equation reduces to an inverse-square Schrodinger-type problem with a quadratic spectral parameter. Imposing a strictly outgoing boundary condition at the singularity-interpreted as irreversible absorption-selects a unique physical realization and converts the fall-to-the-center instability into a discrete, log-periodic spectrum of complex energies. The resulting decay rates exhibit universal geometric spacing, determined solely by the anomalous scaling exponent and insensitive to microscopic short-distance regularization. This structure defines an emergent kinematic energy scale that controls dissipative dynamics and provides a minimal analytic framework for studying scale anomaly, boundary-condition-induced non-Hermiticity, and quantized dissipation in relativistic open quantum systems.

    ↳ quant-phhep-phhep-thPLB(2026)·0 citations
59. 59*

    Hadron Structure from lattice QCD in the context of the Electron-Ion Collider

    Constantia Alexandrou (University of Cyprus & The Cyprus Institute)🇨🇾

    Hadron structure calculations using lattice Quantum Chromodynamics (QCD) have advanced significantly in recent years. Results for charges, form factors, and lower Mellin moments can be obtained to high precision, generalized parton distributions can now be computed either directly or reconstructed from moments, and transverse-momentum-dependent distributions can be accessed through direct lattice calculations. Together, these quantities provide detailed and complementary insights into the internal structure of hadrons. These theoretical developments are highly relevant to the experimental program of the Electron-Ion Collider (EIC) and of other facilities. We review the most pertinent lattice QCD results for hadron structure that inform the EIC scientific agenda, with particular emphasis on the pion, kaon, and nucleon.

    ↳ hep-lathep-phnucl-thPoS(2026)·5 citations
60. 60*

    Scattering in strong field QED in a non-null background

    Patrick Copinger🇯🇵 · James P. Edwards🇬🇧 · Karthik Rajeev🇬🇧

    We examine scattering amplitudes for an arbitrary number of photons in a class of non-null background electromagnetic fields, studying tree-level and one-loop amplitudes in scalar and spinor quantum-electrodynamics in backgrounds defined by a gauge field $A_{\mu }(\mathfrak{n}\cdot x)$ for ${\mathfrak{n}}^2\ne 0$. Motivated to account for more physically realistic laser-plasma dispersive properties, our approach overcomes prior work studying such amplitudes in a constant background field and relaxes the familiar null criterion assumed for plane waves. Master Formulae for the $N$-photon amplitudes dressed by the non-null background are constructed using the first-quantised worldline formalism, which can systematically account for all orders in the non-null parameter, ${\mathfrak{n}}^2$, treated here as an expansion parameter. These are derived from worldline representations of the coordinate and momentum space propagators (and their LSZ-truncated amplitudes) and the effective action, each incorporating the non-null background non-perturbatively. We then outline a partial resummation of their expansions in ${\mathfrak{n}}^2$. A special exactly solvable case of non-null constant crossed fields without photon insertion in the effective action is explored to test the Master Formulae that result. The validity of the presented master formulae is further checked against known expressions for the wavefunction and non-linear Compton scattering in a non-null background to lowest order in the non-null parameter.

    ↳ hep-thhep-phPRD(2026)·1 citation
61. 61*

    Probing soft signals of gravitational-wave memory with space-based interferometers

    Yan Cao🇨🇳 · Yong-Liang Ma🇨🇳 · Yong Tang🇨🇳

    Gravitational-wave displacement memory is a remarkable and ubiquitous phenomenon predicted by general relativity, which has not yet been detected. Unlike the oscillatory components of gravitational waveforms, displacement memory is associated with soft gravitons, making it the only observable signal of its parent event at sufficiently low frequencies. Similarly, soft waveforms may arise from velocity and integrated-displacement memory. The simple and universal spectral shapes of soft waveforms also provide effective templates for matched filtering and parameter estimation. In this paper, we investigate the detection prospects for such soft memory signals with future space-based laser interferometers. As realistic examples, we examine the infrared spectral features of gravitational waves from moderately relativistic compact binary scattering and nearly equal-mass quasi-circular, non-precessing black hole mergers. In both cases, the low frequency spectrum can be described by a corrected soft waveform of displacement memory. The results of simulated Bayesian parameter estimation demonstrate that independent measurement of a soft displacement-memory signal with a single LISA-like detector is achievable at signal-to-noise ratios $\gtrsim 10$. The measurement precision can be significantly improved by joint observations with a LISA-Taiji network. A single BBO detector could be capable of separately measuring the null memory from stellar-mass compact binary mergers. We also evaluate the detectability of an idealized stochastic background of soft displacement-memory signals. Our results indicate that gravitational-wave bursts with memory can be promising targets for space-based interferometers.

    ↳ gr-qcastro-ph.HEhep-ph1 citation
62. 62*

    Effects of Cosmic Muons on $\mu$eV-to-meV Scale Axion Dark Matter Searches

    Dan Zhang🇺🇸 · Gray Rybka🇺🇸 · Edward J. Daw🇬🇧 · Robyn Evren🇬🇧

    We estimate the synchrotron radiation of cosmic muons in a uniform magnetic field in the $\mu$eV-to-meV energy scale. Such events can potentially bring backgrounds to the axion dark matter searches. The GEANT4 software package is utilized to simulate the muon tracks in a cylindrical region of interest with an 8~T solenoid magnetic field applied. We further develop an analytical estimation of the angular-frequency-differential synchrotron radiation power spectra in this work as the cosmic muons span a wide range of Lorentz factor $\gamma$ and pitch angle $\alpha$. We verify that the cosmic muons are not the dominant noise background for the current axion dark matter experiments on the $\mu$eV scale because of the high quality factor $Q$ and fine energy resolution in the readout. However, without sufficient energy resolution in the detector readout, future broadband axion dark matter experiments will be vulnerable to the synchrotron radiation of these charged particles.

    ↳ physics.ins-dethep-exhep-phNew J.Phys.(2026)·0 citations
63. 63*

    Quark-Mass Dependence of Light-Nuclei Masses from Lattice QCD and Trace-Anomaly Contributions to Nuclear Bindings

    Debsubhra Chakraborty🇮🇳 · Noah Chavez🇺🇸 · Xiang Gao🇺🇸 · Nilmani Mathur🇮🇳 · Swagato Mukherjee🇺🇸

    We present lattice QCD calculations of the masses of the deuteron, dineutron, Helium-3 and Helium-4 with physical sea quarks and valence quark masses corresponding to pion masses between 140 and 700 MeV. At the physical point, the lowest finite-volume two-nucleon energy levels exhibit the qualitative pattern of a bound deuteron and an unbound dineutron within uncertainties, while at heavier quark masses they indicate the presence of deeply bound states. Compared with expectations from low-energy effective field theories, the observed mass dependence of the binding energies provides first-principles constraints on the quark-mass dependence of two- and three-nucleon interactions. From the quark-mass variation of the nuclear energies, we determine nuclear sigma terms and quantify the response of light-nuclear masses to changes in the light-quark mass. Using the QCD trace anomaly relation, we decompose the nuclear binding energy into quark-mass and gluonic contributions around the deuteron mass scale of $\mu =2$ GeV. We find that the quark-mass contribution to the binding energy is small and approximately additive in nucleon number within current precision, whereas the gluonic component provides the dominant contribution and show milder increases with mass number.

    ↳ hep-lathep-phnucl-th1 citation

* 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.