Thu·Aug 22, 2024Thursday·August 22, 2024

1. 01*

   The upcoming CTEQ-TEA parton distributions in a nutshell

   A. Ablat🇨🇳 · A. Courtoy🇲🇽 · S. Dulat🇨🇳 · M. Guzzi🇺🇸 · T. J. Hobbs🇺🇸 · T.-J. Hou🇨🇳 · J. Huston🇺🇸 · P. Nadolsky🇺🇸 · I. Sitiwaldi🇨🇳 · K. Xie🇺🇸 · C.-P. Yuan🇺🇸

   We review recent studies by the CTEQ-TEA group toward the development of a new generation of precision parton distribution functions in the nucleon for advanced studies at the high-luminosity LHC and in other experiments. Among several ongoing efforts, we examine sensitivity to the PDFs and mutual compatibility of new measurements in production of Drell-Yan pairs, top-quark pairs, and single-inclusive jets by the ATLAS, CMS, and LHCb collaborations in the LHC Runs 1 and 2.

   hep-phPoS(2025)·3 citations
2. 02*

   Light quark loops in $K^{\pm }\to {\pi }^{\pm }\nu \bar{\nu }$ from vector meson dominance and update on the Kaon Unitarity Triangle

   E. Lunghi🇺🇸 · A. Soni🇺🇸

   We use vector meson dominance to calculate non-perturbative contributions to the branching ratio of the rare decay $K^{\pm }\to {\pi }^{\pm }\nu \bar{\nu }$ stemming from matrix elements involving up-quark loops. The importance of this observable as well as of $K^0\to {\pi }^0{l}^{+}{l}^{-}$ and of the direct CP violation parameter ${ϵ}_K^{\prime }$ is then discussed in the context of a Unitarity Triangle sqtudy based on Kaon sector observables only.

   hep-phhep-exJHEP(2024)·7 citations
3. 03*

   Solving the strong CP problem with massless grand-color quarks

   Ravneet Bedi🇺🇸 · Tony Gherghetta🇺🇸 · Keisuke Harigaya🇺🇸

   We propose a solution to the strong CP problem that specifically relies on massless quarks and has no light axion. The QCD color group $SU(3{)}_c$ is embedded into a larger, simple gauge group (grand-color) where one of the massless, colored fermions enjoys an anomalous chiral symmetry, rendering the strong CP phase unphysical. The grand-color gauge group $G_{\mathrm{GC}}$ is Higgsed down to $SU(3{)}_c\times G_{c^{\prime }}$, after which $G_{c^{\prime }}$ eventually confines at a lower scale, spontaneously breaking the chiral symmetry and generating a real, positive mass to the massless, colored fermion. Since the chiral symmetry has a $G_{c^{\prime }}$ anomaly, there is no corresponding light Nambu-Goldstone boson. The anomalous chiral symmetry can be an accidental symmetry that arises from an exact discrete symmetry without introducing a domain wall problem. Potential experimental signals of our mechanism include vector-like quarks near the TeV scale, pseudo Nambu-Goldstone bosons below the 10 GeV scale, light dark matter decay, and primordial gravitational waves from the new strong dynamics.

   hep-phJHEP(2025)·4 citations
4. 04*

   Towards a first principles light-front Hamiltonian for the nucleon

   Siqi Xu🇨🇳 · Yiping Liu🇨🇳 · Chandan Mondal🇨🇳 · Jiangshan Lan🇨🇳 · Xingbo Zhao🇨🇳 · Yang Li🇨🇳 · James P. Vary🇺🇸

   We solve the nucleon's wave functions from the eigenstates of the light-front quantum chromodynamics Hamiltonian for the first time, using a fully relativistic and nonperturbative approach based on light-front quantization, without an explicit confining potential. These eigenstates are determined for the three-quark, three-quark-gluon, and three-quark-quark-antiquark Fock representations, making them suitable for low-resolution probes. From this, we calculate the nucleon's quark and gluon matter densities, helicity, and transversity distributions, which show qualitative consistency with experimental extractions. We also compute the contributions of quark and gluon helicity to the proton spin and the tensor charges. The obtained light-front wave functions represent a significant advancement towards a unified description of various hadron distribution functions in both longitudinal and transverse momentum space.

   hep-phnucl-thPLB(2025)·24 citations
5. 05*

   Photoproduction $\gamma p\to f_0(980)p$ in an effective Lagrangian approach

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

   The most recent data on differential cross sections and photon beam asymmetries $\Sigma$ from the LEPS2/BGOegg Collaboration for the $\gamma p\to f_0(980)p$ reaction are analyzed within a tree-level effective Lagrangian approach. The $t$-channel $\rho$ and $\omega$ exchanges, the $u$- and $s$-channel $N$ exchanges, the interaction current, and the possible $s$-channel $N^{\ast }$ exchanges are taken into account in constructing the reaction amplitudes to reproduce the data. The results show that the contributions from either the $N(2040)3/2^{+}$ or the $N(2100)1/2^{+}$ resonance exchange in the $s$ channel are necessarily required to describe the LEPS2/BGOegg data and they dominate the differential cross sections of $\gamma p\to f_0(980)p$. Further analysis shows that the contributions from the $t$-channel $\rho$ and $\omega$ exchanges and the interaction current are rather small to both differential cross sections and photo beam asymmetries, and the contributions from $u$-channel $N$ exchange are considerable in the case of including $N(2040)3/2^{+}$ in the model while negligible in the case of including $N(2100)1/2^{+}$ in the model. Predictions of target asymmetries $T$ for $\gamma p\to f_0(980)p$ are given, which can be examined by future experiments.

   hep-phnucl-thPRC(2024)·4 citations
6. 06*

   Closure Testing the MSHT PDFs and a First Direct Comparison to the Neural Net Approach

   L. A. Harland-Lang🇬🇧 · R.S. Thorne🇬🇧 · T. Cridge🇩🇪

   We present a brief overview of the first global closure test of the fixed parameterisation (MSHT) approach to PDF fitting. We find that the default MSHT20 parameterisation can reproduce the features of the input set in such a closure test to well within the textbook uncertainties. This provides strong evidence that parameterisation inflexibility in the MSHT20 fit is not a significant issue in the data region. We also present the first completely like-for-like comparison between two global PDF fits, namely MSHT and NNPDF, where the only difference is guaranteed to be due to the fitting methodology. To achieve this, we present a fit to the NNPDF4.0 data and theory inputs with the MSHT parameterisation. We find that this gives a moderately, but noticeably, better fit quality than the central NNPDF4.0 fits and that this difference persists at the level of the PDFs and benchmark cross sections. The NNPDF4.0 uncertainties are found to be broadly in line with the MSHT results if a textbook $T^2=1$ tolerance is applied, but to be significantly smaller if a tolerance typical of the MSHT20 fit is applied.

   hep-phhep-ex1 citation
7. 07*

   Theoretical study of the open-flavor tetraquark $T_{c\bar{s}}(2900)$ in the process ${\bar{B}}_s^0\to K^0{D}^0{\pi }^0$

   Wen-Tao Lyu🇨🇳 · Man-Yu Duan🇨🇳 · Xiaoyu Wang🇨🇳 · Dian-Yong Chen🇨🇳 · En Wang🇨🇳

   Recently, the LHCb Collaboration has measured two decay processes $B^0\to {\bar{D}}^0{D}_s^{+}{\pi }^{-}$ and $B^{+}\to D^{-}{D}_s^{+}{\pi }^{+}$ related to isospin symmetry, where two new open-flavor tetraquark states $T_{c\bar{s}}(2900{)}^0$ and $T_{c\bar{s}}(2900{)}^{++}$ that belong to an isospin triplet were observed in the $D_s^{+}{\pi }^{-}$ and $D_s^{+}{\pi }^{+}$ invariant mass distributions. In this work, we have investigated the validity of the process ${\bar{B}}_s^0\to K^0{D}^0{\pi }^0$ as the promising process to confirm the existence of $T_{c\bar{s}}(2900{)}^0$ resonance. Taking into account the tetraquark state $T_{c\bar{s}}(2900)$, as well as intermediate resonances $K^{\ast }(892)$, $K_0^{\ast }(1430)$, and $K_2^{\ast }(1430)$, it has been shown that a clear peak of the open-flavor tetraquark $T_{c\bar{s}}(2900)$ appears in the $K^0{D}^0$ invariant mass distribution of the process ${\bar{B}}_s^0\to K^0{D}^0{\pi }^0$, which could be tested by future experiments.

   hep-phEPJC(2025)·6 citations
8. 08*

   Strong decays of $P-$wave doubly charmed and bottom baryons

   Ya-Li Shu🇨🇳 · Qing-Fu Song🇨🇳 · Qi-Fang Lü🇨🇳

   In this work, we investigate the strong decays for $P-$wave excited states of doubly charmed and bottom baryons in the constituent quark model. Our results indicate that some $\lambda -$mode ${\Xi }_{cc/bb}(1P)$ and ${\Omega }_{cc/bb}(1P)$ states are relatively narrow, which are very likely to be discovered by future experiments. The light meson emissions for the low-lying $\rho -$mode states are highly suppressed due to the orthogonality of wave functions between initial and final states. Moreover, the strong decay behaviors for doubly charmed and bottom baryons preserve the heavy superflavor symmetry well, where the small violation originates from the finite heavy quark masses and different phase spaces. We hope that present theoretical results for undiscovered doubly charmed and bottom baryons can provide helpful information for future experiments and help us to better understand the heavy quark symmetry.

   hep-phhep-exnucl-thCommun.Theor.Phys.(2026)·3 citations
9. 09*

   Single- and double-unresolved limits of polarized tree-level matrix elements

   Thomas Gehrmann🇨🇭 · Markus Löchner🇨🇭

   The calculation of exclusive cross sections at next-to-next-to-leading order (NNLO) in QCD requires an analytic understanding of the infrared singular structure with up to two unresolved partons. This has so far only been achieved for unpolarized matrix elements. We derive the full set of splitting amplitudes arising in longitudinally polarized tree-level QCD matrix elements at NNLO in the Larin ${\gamma }_5$ scheme. They are extracted from DIS-like processes, and are verified in matrix elements of higher multiplicity. Our results will enable the calculation of NNLO corrections to longitudinal spin asymmetries in polarized collider processes.

   hep-phPoS(2025)·0 citations
10. 10*

    Exploring Axion-Like Particle Couplings through Single Top $tW$-Channel and Top Pair Production at the LHC

    Yasaman Hosseini🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

    In this paper, we explore the interactions between light axion-like particles (ALPs) and top quarks, gluons, and W-bosons. Utilizing high-energy probes at the LHC, we probe these couplings in the context of single top quark production associated with a W-boson and an ALP. We analyze the latest LHC Run II data on $t\bar{t}$ spin correlation measurements to establish constraints on these couplings. Additionally, we compare these constraints with those derived from loop-induced couplings and indirect searches involving B-meson decays. Furthermore, we derive two-dimensional limits on the ALP couplings with top quarks and gluons.

    hep-phPRD(2024)·8 citations
11. 11*

    How the QCD trace anomaly behaves at the core of twin stars?

    José C. Jiménez🇧🇷 · Lucas Lazzari🇧🇷 · Victor P. Gonçalves🇧🇷

    We investigate the behavior of the dense and cold (normalized) QCD trace anomaly, $\Delta$, in the interior of twin neutron stars (obtained from several sets of equations of state in agreement with modern compact-star and multimessenger data) satisfying static and dynamic stability conditions. We scan the formed twin-star parameter space in order to look for effects caused by the presence of a strong first-order phase transition connecting hadron and quark phases by means of a Maxwell construction. We found robustly that $\Delta$ suffers an abrupt decrease around the transition point, even reaching large negative values ($\Delta \simeq -0.35$), in marked contrast to current studies pointing out a smooth behavior with $\Delta \gtrsim 0$ at all densities. Besides, we characterize the behavior of {the recently defined} conformal factor, $d_c$, in our four categories of twin stars for which we perform comparisons with theoretical constraints put, e.g. by Bayesian studies sometimes adjusted to agree with perturbative QCD at high densities. These analyses allow us to hypothesize modifications in the strong QCD coupling in dense nuclear matter with a strong thermodynamic discontinuity.

    hep-phgr-qchep-latnucl-thPRD(2024)·22 citations
12. 12*

    RODEM Jet Datasets

    Knut Zoch🇨🇭 · John Andrew Raine🇨🇭 · Debajyoti Sengupta🇨🇭 · Tobias Golling🇨🇭

    We present the RODEM Jet Datasets, a comprehensive collection of simulated large-radius jets designed to support the development and evaluation of machine-learning algorithms in particle physics. These datasets encompass a diverse range of jet sources, including quark/gluon jets, jets from the decay of W bosons, top quarks, and heavy new-physics particles. The datasets provide detailed substructure information, including jet kinematics, constituent kinematics, and track displacement details, enabling a wide range of applications in jet tagging, anomaly detection, and generative modelling.

    hep-ph4 citations
13. 13*

    Exploring Abelian-Non-Abelian Kinetic Mixing in SMEFT and Beyond

    Van Que Tran🇨🇳 · Tzu-Chiang Yuan🇹🇼

    We explore a novel scenario involving Abelian-non-Abelian kinetic mixing within the framework of the Standard Model Effective Field Theory (SMEFT) and its extension with a real triplet scalar field. In SMEFT, this mixing arises exclusively from a dimension-6 operator involving the Standard Model Higgs doublet, while the real triplet scalar field introduces an additional dimension-5 operator. We derive the modifications to electroweak gauge boson properties and impose constraints using electroweak precision data. In SMEFT, we find that $Z$ pole data at LEP-I imposes a stringent constraint on the kinetic mixing parameter, requiring it to be less than $O$($10^{-4}$), which corresponds to a new physics scale of about 10 TeV. In the SMEFT+triplet scenario, the constraint can be significantly relaxed with a sizeable triplet vacuum expectation value while preserving custodial symmetry in a finely-tuned parameter space. Future measurements from the Circular Electron Positron Collider could probe the kinetic mixing parameter down to an order of magnitude smaller.

    hep-phPRD(2025)·3 citations
14. 14*

    Variational autoencoder inverse mapper for extraction of Compton form factors: Benchmarks and conditional learning

    Fayaz Hossen🇺🇸 · Douglas Adams🇺🇸 · Joshua Bautista🇺🇸 · Yaohang Li🇺🇸 · Gia-Wei Chern🇺🇸 · Simonetta Liuti🇺🇸 · Marie Boer🇺🇸 · Marija Cuic🇺🇸 · Gari R. Goldstein🇺🇸 · Michael Engelhardt🇺🇸 · Huey-Wen Li🇺🇸

    Deeply virtual exclusive scattering processes (DVES) serve as precise probes of nucleon quark and gluon distributions in coordinate space. These distributions are derived from generalized parton distributions (GPDs) via Fourier transform relative to proton momentum transfer. QCD factorization theorems enable DVES to be parameterized by Compton form factors (CFFs), which are convolutions of GPDs with perturbatively calculable kernels. Accurate extraction of CFFs from DVCS, benefiting from interference with the Bethe-Heitler (BH) process and a simpler final state structure, is essential for inferring GPDs. This paper focuses on extracting CFFs from DVCS data using a variational autoencoder inverse mapper (VAIM) and its constrained variant (C-VAIM). VAIM is shown to be consistent with Markov Chain Monte Carlo (MCMC) methods in extracting multiple CFF solutions for given kinematics, while C-VAIM effectively captures correlations among CFFs across different kinematic values, providing more constrained solutions. This study represents a crucial first step towards a comprehensive analysis pipeline towards the extraction of GPDs.

    hep-ph7 citations
15. 15*

    Tau polarization effects in ${\nu }_{\tau }/{\bar{\nu }}_{\tau }$-tungsten interactions at the LHC energies

    Reinaldo Francener🇧🇷 · Victor P. Goncalves🇧🇷 · Diego R. Gratieri🇧🇷

    Recent studies have demonstrated that the tau produced in charged current neutrino deeply inelastic interactions at the GeV -- TeV neutrino energy range is not fully polarized. In this paper we investigate the impact of the tau polarization on the pions generated in its decay. In particular, we consider tau neutrino - tungsten interactions at the LHC energies and estimate the associated pion momentum, energy and angular distributions. The contribution of the $F_5$ is also investigated. Our results indicate that the pion properties are sensitive to the tau polarization state as well as to the magnitude of $F_5$.

    hep-phPRD(2024)·3 citations
16. 16*

    Vector leptoquark contributions to lepton dipole moments

    Arvind Bhaskar🇮🇳 · Diganta Das🇮🇳 · Soumyadip Kundu🇮🇳 · Anirudhan A. Madathil🇺🇸 · Tanumoy Mandal🇮🇳 · Subhadip Mitra🇮🇳

    Leptoquarks (LQs) can contribute to the magnetic and electric dipole moments of charged leptons, which the current experiments have measured with good accuracy. We revisit the parameter spaces of TeV-scale vector LQs that contribute to these observables and study how these models fare against the LHC bounds. We show that significant portions of the parameter space are excluded when the current LHC data is utilised effectively. We find that only $U_1$ and $V_2$ can explain the observed positive shift in $(a_{\mu }^{\exp }-a_{\mu }^{\mathrm{SM}})$ through a lepton chirality-flipping contribution with $\mathcal{O}(1)$ LQ-quark-lepton coupling. We also see how these two LQs can fit the electron dipole moment and atomic parity violation measurements. We find that the current electric dipole moment measurements of the muon cannot restrain the LQ-quark-lepton couplings within perturbative regions.

    hep-phhep-exPRD(2025)·7 citations
17. 17*

    Nonminimal Superheavy Dark Matter

    Sarunas Verner🇺🇸

    We investigate the gravitational production of superheavy scalar fields with nonminimal coupling during and after inflation. We derive analytical approximations using the mode function solution in a de Sitter background and also apply the steepest descent method. We study both positive and negative nonminimal couplings and show that their comoving number density spectra behave differently in the short and long wavelength regimes. We numerically compute the comoving number density spectra and dark matter abundance for a broad range of superheavy spectator fields exceeding the Hubble scale during inflation, with $m_{\chi }>H_I$, and nonminimal couplings ranging from $-300\le \xi \le 300$. When computing the allowed dark matter parameter space, we impose the maximum reheating temperature constraint, the Big Bang nucleosynthesis constraint, and the isocurvature constraint. We show that the presence of a positive or negative coupling $\xi$ can expand the parameter space up to $3$ orders of magnitude above the Hubble inflationary scale, allowing such dark matter candidates to be as heavy as $\sim 10^{16}\mathrm{GeV}$ in the Starobinsky model of inflation.

    hep-phastro-ph.COgr-qcJCAP(2025)·17 citations
18. 18*

    Neutrino Nonstandard Interactions and Lepton Flavor Universality violation at SND@LHC via charm production

    Bhubanjyoti Bhattacharya🇺🇸 · Alakabha Datta🇺🇸 · Elena Graverini🇮🇹 · Lopamudra Mukherjee🇨🇳 · Divya Sachdeva🇫🇷 · John Waite🇺🇸

    In this work, we explore the effect of neutrino nonstandard interactions (NSI) involving the charm quark at SND@LHC. Using an effective description of new physics in terms of four-fermion operators involving a charm quark, we constrain the Wilson coefficients of the effective interaction from two and three-body charmed meson decays. In our fit, we include charmed meson decays not only to pseudoscalar final states but also to vector final states and include decays to the $\eta$ and ${\eta }^{\prime }$ final states. We also consider constraints from charmed baryon decays. We then study the effect of new physics in neutrino scattering processes, involving charm production at SND@LHC, for various benchmark new physics couplings obtained from the low energy fits. Finally, we also study the effects of lepton universality violation (LUV) assuming that the new physics coupling is not lepton universal.

    hep-phhep-exJHEP(2024)·0 citations
19. 19*

    Anapole moment of neutrinos and radioactive sources near liquid xenon detectors

    Gonzalo Herrera🇺🇸 · Patrick Huber🇺🇸

    We show that placing a radioactive source such as ${}^{51}$Cr near a liquid xenon detector may allow to detect the contribution induced by the anapole moment to neutrino-electron scattering in the Standard Model at the 1-2 $\sigma$ level. Although the anapole moment of neutrinos induces a scattering rate with the same spectral shape as the neutral and charged current contributions, exposures of $\sim$ 60 tonne $\times$ source run at XENONnT or XLZD may be enough to accumulate sufficient statistics for a detection. We also discuss a simple model where the anapole moment of neutrinos is enhanced or decreased with respect to the SM expectation, further demonstrating how a potential measurement of the anapole moment of neutrinos would allow to constrain new physics.

    hep-phhep-exPRD(2025)·10 citations
20. 20*

    Colour-electric and colour-magnetic confinement

    N.O. Agasian🇷🇺 · Z.V. Khaidukov🇷🇺 · M.S. Lukashov🇷🇺 · Yu.A. Simonov🇷🇺

    The basic properties of the confinement mechanism in QCD -- the temperature dependence of the spatial and temporal string tensions (${\sigma }_s(T)$ and ${\sigma }_E(T)$) -- are studied in the framework of the Field Correlator Method (FCM). It is shown that both functions are connected respectively to the spatial and temporal parts of the vacuum gluon energy ${ϵ}_s$ and ${ϵ}_E$ which define their equal values at $T=0$. However at $T>0$ the spatial part is growing with $T$ while the temporal part is destroyed by the hadronic pressure at $T=T_c$ (the deconfinement). Both properties are derived within the same method and are in a good agreement with the corresponding lattice data.

    hep-phhep-latPhys.Part.Nucl.(2024)·0 citations
21. 21*

    Holographic thermodynamic relation for dissipative and non-dissipative universes in a flat FLRW cosmology

    Nobuyoshi Komatsu🇯🇵

    To clarify a holographic modified thermodynamic relation, the present study applies a general formulation for cosmological equations in a flat FLRW universe to the first law of thermodynamics, using the Bekenstein-Hawking entropy $S_{\mathrm{BH}}$ and a dynamical Kodama-Hayward temperature $T_{\mathrm{KH}}$. For the general formulation, both an effective pressure $p_e$ of cosmological fluids for dissipative universes (e.g., bulk viscous cosmology) and an extra driving term $f_{\Lambda }(t)$ for non-dissipative universes (e.g., time-varying $\Lambda (t)$ cosmology) are phenomenologically assumed. When $f_{\Lambda }(t)$ is constant, the modified thermodynamic relation is equivalent to the formulation of the first law in standard cosmology. One side of this modified relation describes thermodynamic quantities in the bulk and can be divided into two time-derivative terms, namely $\dot{\rho }$ and $\dot{V}$ terms, where $\rho$ is the mass density of cosmological fluids and $V$ is the Hubble volume. Using the Gibbons-Hawking temperature $T_{\mathrm{GH}}$, the other side of this relation, $T_{\mathrm{KH}}{\dot{S}}_{\mathrm{BH}}$, can be formulated as the sum of $T_{\mathrm{GH}}{\dot{S}}_{\mathrm{BH}}$ and $[(T_{\mathrm{KH}}/T_{\mathrm{GH}})-1]T_{\mathrm{GH}}{\dot{S}}_{\mathrm{BH}}$, which are equivalent to the $\dot{\rho }$ and $\dot{V}$ terms, respectively, with the magnitude of the $\dot{V}$ term being proportional to the square of the $\dot{\rho }$ term. In addition, the modified thermodynamic relation for constant $f_{\Lambda }(t)$ is examined by applying the equipartition law of energy on the horizon. This modified thermodynamic relation reduces to a kind of extended holographic-like connection when a constant $T_{\mathrm{KH}}$ universe is considered. The evolution of thermodynamic quantities is also discussed, using a constant $T_{\mathrm{KH}}$ model, extending a previous analysis [Phys. Rev. D 108, 083515 (2023) (arXiv:2306.11285)].

    ↳ gr-qcastro-ph.COhep-phEPJC(2025)·4 citations
22. 22*

    Scrutinizing the Isotropic Gamma-Ray Background in Search of Dark Matter

    Ilias Cholis🇺🇸 · Iason Krommydas🇺🇸

    The isotropic gamma-ray background (IGRB), measured by the Fermi Large Area Telescope, is the result of several classes of extragalactic astrophysical sources. Those sources include blazars, start-forming galaxies and radio galaxies. Also, ultra-high-energy cosmic rays interacting with the infrared background, contribute to the isotropic background. Using information from Fermi's gamma-ray sources catalog and the results of dedicated studies of these classes of sources, from observations at the infrared and radio, we model their contribution to the IGRB. In addition to conventional astrophysical sources, dark matter may be a component of the IGRB. We combine our model of conventional astrophysical sources and of dark matter annihilation in distant galaxies, marginalizing over relevant uncertainties, to derive constraints on the dark matter annihilation cross section, from the measured IGRB. In calculating the contribution from dark matter we include the flux from extragalactic halos and their substructure and also the subdominant contribution from Milky Way's halo at high galactic latitudes. The resulting constraints are competitive with the strongest current constraints from the dwarf spheroidal galaxies. Under certain dark matter assumptions, we also find an indication for a small excess flux in the isotropic background. Our results are consistent with the gamma-ray excess at GeV energies toward the galactic center.

    ↳ astro-ph.HEhep-phPRD(2024)·7 citations
23. 23*

    A topological contribution to Bogoliubov coefficient for cosmological particle production

    Daniel J. H. Chung🇺🇸 · Nidhi Sudhir🇺🇸

    Particle production in cosmology is often efficiently computed in terms of Bogoliubov transforms. Restricting to a particular class of dispersion relationships, we identify a map between the number of particles produced in a special kinematic limit and a Stokes phenomena related topology of analytic continuation of the Bogoliubov coefficient functions. Intuitively, this kinematic limit corresponds to the long wavelength limit although a more precise description depends on the nature of the curved spacetime. To identify the topology, we reformulate the usual Bogoliubov computations as a type of SU(1,1) gauged differential equation and utilize a special gauge together with a discrete symmetry that naturally characterizes the dispersion relationship. Using a dark matter model and a nonzero constant spatial curvature model, we estimate how such topological contributions will arise in physical applications.

    ↳ hep-thgr-qchep-phPRD(2025)·3 citations
24. 24*

    Second-order spin hydrodynamics from Zubarev's nonequilibrium statistical operator formalism

    Abhishek Tiwari🇮🇳 · Binoy Krishna Patra🇮🇳

    Using the Zubarev's nonequilibrium statistical operator formalism, we derive the second-order expression for the dissipative tensors in relativistic spin hydrodynamics, {\em viz.} rotational stress tensor (${\tau }_{\mu \nu }$), boost heat vector ($q_{\mu }$), shear stress tensor (${\pi }_{\mu \nu }$), and bulk viscous pressure ($\Pi$). The first two (${\tau }_{\mu \nu }$ and $q_{\mu }$) emerge due to the inclusion of the antisymmetric part in the energy-momentum tensor, which, in turn, governs the conservation of spin angular momentum (${\Sigma }^{\alpha \mu \nu }$). As a result, new thermodynamic forces, generated due to the antisymmetric part of $T_{\mu \nu }$, contain the spin chemical potential. In this work, we have also taken the spin density ($S^{\mu \nu }$) as an independent thermodynamic variable, in addition to the energy density and particle density, thereby resulting in two novel transport coefficients given by the correlation between spin density tensor and rotational stress tensor and vice versa. Additionally, the newly found terms in ${\pi }_{\mu \nu }$ and $\Pi$ are the artifacts of the new thermodynamic forces that arise due to the antisymmetric part of $T^{\mu \nu }$. Finally, we have derived the evolution equations for the aforesaid tensors: ${\tau }_{\mu \nu }$, $q_{\mu }$, ${\pi }_{\mu \nu }$, and $\Pi$.

    ↳ hep-thhep-phnucl-thPRD(2025)·19 citations
25. 25*

    An Impact of Parton Distribution Functions on Open Heavy Flavor Azimuthal Angular Correlations in Pb-Pb Collisions at $\sqrt{s_{NN}}$ = 5.5 TeV

    Swapnesh Khade🇮🇳 · Ravindra Singh🇩🇪 · Yoshini Bailung🇮🇳 · Ankhi Roy🇮🇳

    In this paper, we investigate the impact of modern free parton distribution functions and nuclear parton distribution functions on the azimuthal angular correlation of open heavy flavor hadrons in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.5 TeV using PYTHIA8 + Angantyr model. The method involves a transverse momentum ($p_{\mathrm{T}}$) differential assessment of azimuthal angular correlations between prompt ${\mathrm{D}}^0-{\bar{\mathrm{D}}}^0$ and $\mathrm{B}-\bar{\mathrm{B}}$. By analyzing the $p_{\mathrm{T}}$-dependent behavior of these correlations, we probe the interplay between different production mechanisms and assess the impact of parton distribution functions on heavy-flavor hadron production dynamics. Our results indicate that nuclear parton distribution functions significantly modify both near-side and away-side peaks of the azimuthal correlation distribution compared to the default PYTHIA8 baseline, particularly at low $p_{\mathrm{T}}$. The near-side double-peak structure suggests contributions from next-to-leading order (NLO) processes, such as gluon splitting, and its presence is strongly correlated with the number of hard multi-partonic interactions. Additionally, by quantitatively comparing the change in correlation widths across various PDF settings, we comment on the role of nuclear parton distribution functions in heavy-quark thermalization in heavy-ion collisions. This comprehensive study of azimuthal correlations enhances our understanding of initial-state conditions and heavy-flavor production dynamics in nuclear collisions.

    ↳ hep-exhep-phNPA(2025)·1 citation
26. 26*

    Motivating Gauge-Invariant Approaches to Particle Physics

    Philipp Berghofer🇦🇹

    There is noticeable consensus among physicists and philosophers that only gauge-invariant quantities can be physically real. However, this insight that physical quantities must be gauge-invariant is not well-reflected in standard approaches to particle physics. For instance, each and every elementary field/particle of the Standard Model fails to be gauge-invariant! The main objective of this paper is to offer an accessible, concise, and convincing analysis of why philosophers and physicists should devote more of their energy to working on gauge-invariant approaches. Correspondingly, the thesis of this paper is that pursuing gauge-invariant approaches has several virtues. For instance, gauge-invariant reformulations allow us to make particle physics consistent with the mathematical framework in which it is formulated. This is illustrated by how mathematical theorems such as Elitzur's theorem, the Gribov ambiguity, and Haag's theorem pose problems for standard approaches but are avoided by gauge-invariant approaches.

    ↳ physics.hist-phhep-phhep-thPoS(2026)·0 citations
27. 27*

    Surface Kinematics and "The" Yang-Mills Integrand

    Nima Arkani-Hamed🇺🇸 · Qu Cao🇨🇳 · Jin Dong🇨🇳 · Carolina Figueiredo🇺🇸 · Song He🇨🇳

    It has been a long-standing challenge to define a canonical loop integrand for non-supersymmetric gluon scattering amplitudes in the planar limit. Naive integrands are inflicted with $1/0$ ambiguities associated with tadpoles and massless external bubbles, which destroy integrand-level gauge invariance as well as consistent on-shell factorization on single loop-cuts. In this letter, we show that this essentially kinematical obstruction to defining "the" integrand for Yang-Mills theory has a structural solution, handed to us by the formulation of gluon amplitudes in terms of curves on surfaces. This defines "surface kinematics" generalizing momenta, making it possible to define "the" integrand satisfying both a (surface generalized) notion of gauge-invariance and consistent loop-cuts. The integrand also vanishes at infinity in appropriate directions, allowing it to be recursively computed for non-supersymmetric Yang-Mills theory in any number of dimensions. We illustrate these ideas through one loop for all multiplicity, and for the simplest two-loop integrand.

    ↳ hep-thhep-phPRL(2025)·45 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.