Understanding Parton Distributions from Lattice QCD: Present Limitations and Future Promise

TL;DR

This paper discusses how lattice QCD calculations of nucleon quark distributions are advancing, addressing previous discrepancies with experiments through chiral extrapolation and highlighting the computational challenges involved.

Contribution

It presents a comprehensive approach to calculating nucleon moments in full QCD and resolves earlier conflicts with experimental data via chiral extrapolation techniques.

Findings

Ground state matrix elements have been calculated in full QCD.

Chiral extrapolation including pion cloud physics resolves conflicts with experimental results.

Computational resource requirements for definitive comparisons are discussed.

Abstract

This talk will explain how ground state matrix elements specifying moments of quark density and spin distributions in the nucleon have been calculated in full QCD, show how physical extrapolation to the chiral limit including the physics of the pion cloud resolves previous apparent conflicts with experiment, and describe the computational resources required for a definitive comparison with experiment.