PaperPanorama

HEP Lattice·hep-lat

Tue·Sep 22, 2026

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    First-Principles Determination of the QCD Contribution to the Axion-Photon Coupling Using Domain-Wall Fermions

    Tian Lin · Hao-Yang Cheng · Xu Feng · Lu-Chang Jin · Chuan Liu · Qi-Yuan Luo

    The axion-photon coupling, crucial for experimental axion searches and tests of the strong CP solution, receives a substantial model-independent contribution from QCD dynamics. Next-to-leading-order chiral perturbation theory (NLO ChPT) in different frameworks has yielded puzzling discrepancies of up to , motivating precise first-principles calculations. We present an independent lattice QCD determination using a method complementary to the recent background-field calculation. Computing pseudoscalar-to-two-photon three-point functions and exploiting anomalous Ward identities, we separate into an exact anomaly contribution and a light-quark-mass-suppressed correction. The latter is computed using domain-wall fermions, whose excellent chiral symmetry strongly suppresses discretization effects. Working on two near-physical ensembles with continuum extrapolation, we obtain (isospin-symmetric), (isospin-breaking), and in total. While direct comparisons with published NLO ChPT predictions reveal apparent tensions, we identify their sources and show that the ChPT results can be reconciled with our lattice determination. Our result provides a first-principles benchmark for the QCD contribution to the axion-photon coupling and a quantitative test of competing ChPT descriptions.

    hep-lathep-exhep-ph
  2. 02

    Flowed quark field renormalization in lattice QCD: A Ward-identity approach and its validation using quark bilinears

    Mei-Qi Gao · Long-cheng Gui · Jun Hua · Jian Liang · Jun Shi

    We present a non-perturbative Ward-identity prescription for determining the flowed quark field renormalization factor , avoiding the computational difficulties of the conventional ringed prescription. The method is based on vector-current normalization and ratios of flowed and unflowed meson two-point functions. We determine the resulting on five -flavor clover ensembles and validate it in the pseudoscalar, scalar, axial-vector, and tensor channels. Renormalized matrix elements obtained through sequential continuum and zero-flow-time extrapolations agree with independent RI/MOM and RI/SMOM determinations. The finite-lattice-spacing bilinear renormalization factors show differences that decrease toward finer lattices, reflecting the different discretization effects of the renormalization methods. The cross-channel agreement demonstrates the viability of the proposed prescription; together, the method and its systematic validation establish a robust foundation for the non-perturbative renormalization of flowed fermionic operators in future lattice calculations.

    hep-lat
  3. 03

    Tackling the noisy truncated moment problem with Gaussian Processes: An application to parton distribution functions

    Rohith Karur

    In this work, we study the noisy truncated Hausdorff moment problem in the context of recovering parton distribution functions (PDFs) from their moments. We start by reviewing basics of the Hausdorff moment problem and analyze how the relation between the amount of moment data provided and the ability for to be reconstructed varies across different classes of parton distribution functions; we then turn to using Bayesian methods centered around Gaussian Processes (GPs) to solve the moment problems. Standard aspects of Bayesian regression such as covariance kernel choice, analytical characterization of the posterior, hyperparameter sampling with Monte Carlo methods, and validation metrics are detailed. In addition to this, powerful novel tools, such as a method to correct for mean bias in posterior distributions, and a simple class of covariance kernels whose correlation length is learned during sampling are introduced. Finally, we test our framework on 5 datasets from valence, gluon, and sea quark phenomenological pion and nucleon PDF datasets, selected to reflect diversity in PDF behavior. We find that our GP framework robustly reconstructs PDFs given a moderate number of moments. Additionally, the novel tools developed in this work resolve persistent issues that would be difficult to address via conventional means. The presented framework can be readily applied to moments obtained via lattice Quantum Chromodynamics (LQCD) to reconstruct PDFs from theoretical first principles.

    ↳ hep-phhep-lat
  4. 04

    Spectroscopic parameters of meson

    Sinem Küçükyılmaz · Halil Mutuk

    We investigate the spectroscopic and decay properties of the meson within a nonrelativistic quark model. We calculate the mass spectrum of radially and orbitally excited states in the -, -, and -wave sectors, the pseudoscalar and vector decay constants with one-loop QCD corrections, the E1 and M1 radiative widths, and radial Regge trajectories. The ground state and its first radial excitation agree well with experiment. The predicted decay constants are in line with relativistic model estimates and yield a corresponding prediction for the leptonic decay . The E1 transition pattern is governed primarily by radial-wave-function overlaps, and the dominant transitions of the lowest -wave multiplet suggest the radiative cascade as a promising pathway to the unobserved -wave states. The model predicts an inverted fine-structure ordering in the - and -wave multiplets, reflecting the competition between the one-gluon-exchange (OGE) and confinement contributions to the spin--orbit interaction. The allowed M1 widths are strongly suppressed by the small predicted hyperfine splittings, highlighting the importance of a direct mass measurement. The radial Regge trajectories are nearly linear across all considered families, with slopes decreasing as the orbital angular momentum increases. These results identify the mass and the fine-structure ordering of the lowest -wave multiplet as the key measurements for testing the spin-dependent dynamics of the system.

    ↳ hep-phhep-exhep-latnucl-th