Nucleon Parton Distribution Functions from Boosted Correlations in the Coulomb gauge
Brookhaven National Laboratory（布鲁克海文国家实验室）；University of Maryland（马里兰大学）；Argonne National Laboratory（阿贡国家实验室）；Massachusetts Institute of Technology（麻省理工学院）
Recently, a novel approach has been proposed to compute parton distributions through the use of boosted correlators fixed in the Coulomb gauge from lattice QCD, within the framework of Large-Momentum Effective Theory (LaMET). This approach circumvents the need for Wilson lines, potentially enhancing the efficiency and accuracy of lattice calculations. In this work, we present the first exploratory implementation of the Coulomb gauge method for calculating nucleon unpolarized, helicity, and transversity parton distribution functions (PDFs). The calculations are performed on a Highly-Improved-Staggered-Quark ensemble with lattice spacing $a = 0.06$ fm, volume $L_s^3 \times L_t=48^3\times 64$, and valence pion mass $m_π=300$ MeV, employing boosted nucleon states with momenta up to 3.04 GeV. Our lattice predictions for the valence-quark PDFs -- extracted from the real part of the correlators -- show good convergence with increasing nucleon momentum and are compatible with the most recent global analyses for all spin structures. On the other hand, the full-quark-channel PDFs obtained from the imaginary part of the correlators exhibit discrepancies between the two large nucleon momenta considered, although the results at the higher momentum are consistent with phenomenology. The discrepancies are likely driven by stronger excited-state contamination in the imaginary matrix elements, which is consistent with the observation in the literature. Overall, this work demonstrates the efficacy of the Coulomb gauge approach for nucleon PDFs and serves as a benchmark for its broader applications.
Direct calculation of parton distributions in momentum space from lattice QCD
University of Maryland（马里兰大学）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；Massachusetts Institute of Technology（麻省理工学院）；Argonne National Laboratory（阿贡国家实验室）
Lattice QCD Benchmark of Proton Helicity and Flavor-Dependent Unpolarized Transverse Momentum-Dependent Parton Distribution Functions at Physical Quark Masses
LaMET-Agent: An Agent Framework for Large-Momentum Effective Theory Analysis
Fermi National Accelerator Laboratory（费米国家加速器实验室）；University of Maryland（马里兰大学）；Argonne National Laboratory（阿贡国家实验室）；Indiana University（印第安纳大学）；Brookhaven National Laboratory（布鲁克海文国家实验室）；The Chinese University of Hong Kong, Shenzhen（香港中文大学（深圳））
