Complementarity of experimental and lattice QCD data on pion parton distributions

TL;DR

This paper combines experimental data and lattice QCD calculations to improve the determination of pion parton distribution functions, reducing uncertainties and analyzing systematic effects.

Contribution

It introduces a comprehensive analysis integrating experimental and lattice QCD data to accurately extract pion PDFs and assess systematic uncertainties.

Findings

Reduced Ioffe time pseudo-distributions decrease PDF uncertainties.

Current-current correlators are limited by lattice systematic effects.

Valence quark distribution behaves as (1-x)^{1.0-1.2} at large momentum fraction.

Abstract

We extract pion parton distribution functions (PDFs) in a Monte Carlo global QCD analysis of experimental data together with reduced Ioffe time pseudo-distributions and matrix elements of current-current correlators generated from lattice QCD. By including both experimental and lattice QCD data, our analysis rigorously quantifies both the uncertainties of the pion PDFs and systematic effects intrinsic to the lattice QCD observables. The reduced Ioffe time pseudo-distributions significantly decrease the uncertainties on the PDFs, while the current-current correlators are limited by the systematic effects associated with the lattice. Consistent with recent phenomenological determinations, the behavior of the valence quark distribution of the pion at large momentum fraction is found to be $\sim (1-x)^{ \beta_{\rm eff}}$ with $\beta_{\rm eff} \approx 1.0-1.2$.