Insights into the Nucleon Spin from Lattice QCD

TL;DR

This paper discusses recent progress in calculating the elusive flavor singlet contributions to the nucleon spin using lattice QCD, overcoming computational challenges posed by disconnected quark diagrams.

Contribution

It presents new lattice QCD methods to directly compute sea quark contributions to nucleon spin, advancing understanding of nucleon structure.

Findings

Successful calculation of sea quark contributions

Improved techniques for disconnected diagram evaluation

Enhanced understanding of nucleon spin composition

Abstract

Flavour singlet contributions to the nucleon spin are elusive due to the fact that they cannot be determined directly in experiment but require extrapolations to the small x region. Direct calculations of these contributions are possible using Lattice QCD, however, they pose a significant computational challenge due to the presence of disconnected quark line diagrams. We report on recent progress in determining these sea quark contributions on the lattice.