Gluon Quasi-PDF From Lattice QCD

TL;DR

This paper pioneers the extraction of the gluon unpolarized parton distribution function's x-dependence from lattice QCD simulations using the LaMET approach, providing initial insights into gluon structure.

Contribution

It is the first lattice QCD attempt to determine the gluon PDF's x-dependence using LaMET, with results consistent with global fits within uncertainties.

Findings

Results agree with global fit PDFs within statistical and systematic uncertainties.

First lattice-based gluon PDF extraction using LaMET.

Demonstrates feasibility of accessing gluon distributions from lattice QCD.

Abstract

We present the first attempt to access the $x$-dependence of the gluon unpolarized parton distribution function (PDF), based on lattice simulations using the large-momentum effective theory (LaMET) approach. The lattice calculation is carried out with pion masses of 340 and 678 MeV on a 2+1-flavor DWF configuration with lattice spacing $a=0.111$~fm, for the gluon quasi-PDF matrix element with the nucleon momentum up to 0.93 GeV. Taking the normalization from similar matrix elements in the rest frame of the nucleon and pion, our results for these matrix elements are consistent with the Fourier transform of the global fit CT14 and PDF4LHC15 NNLO of the gluon PDF, within statistical uncertainty and the systematic one up to power corrections, perturbative ${\cal O}(\alpha_s)$ matching and the mixing from the quark PDFs.