Gluon Parton Distribution of the Pion from Lattice QCD

TL;DR

This paper presents the first lattice QCD calculation of the pion's gluon distribution as a function of momentum fraction, using the pseudo-PDF approach with multiple lattice spacings and pion masses, and compares results with global fits.

Contribution

First lattice QCD determination of the pion gluon distribution using the pseudo-PDF method across various lattice parameters.

Findings

Gluon distribution shows mild dependence on lattice spacing and pion mass.

Results at the lightest pion mass are consistent with global fit determinations.

Method demonstrates feasibility of extracting gluon PDFs from lattice QCD.

Abstract

We present the first determination of the $x$-dependent pion gluon distribution from lattice QCD using the pseudo-PDF approach. We use lattice ensembles with 2+1+1 flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration, at two lattice spacings $a\approx 0.12$ and 0.15~fm and three pion masses $M_\pi\approx 220$, 310 and 690 MeV. We use clover fermions for the valence action and momentum smearing to achieve pion boost momentum up to 2.29 GeV. We find that the dependence of the pion gluon parton distribution on lattice spacing and pion mass is mild. We compare our results from the lightest pion mass ensemble with the determination by JAM and xFitter global fits.