Recent results for the proton spin decomposition from lattice QCD

TL;DR

This paper reports recent non-perturbative lattice QCD results on the proton spin decomposition, including generalized form factors for quark and gluon angular momentum, advancing understanding of proton spin structure.

Contribution

It provides new lattice QCD calculations of generalized form factors at physical pion mass, including initial results on gluon angular momentum, contributing to the proton spin decomposition debate.

Findings

Generalized form factors computed at physical pion mass

Results for quark total spin and angular momentum

Initial findings on gluon angular momentum

Abstract

The exact decomposition of the proton spin has been a much debated topic, on the experimental as well as the theoretical side. In this talk we would like to report on recent non-perturbative results and ongoing efforts to explore the proton spin from lattice QCD. We present results for the relevant generalized form factors from gauge field ensembles that feature a physical value of the pion mass. These generalized form factors can be used to determine the total spin and angular momentum carried by the quarks. In addition we present first results for our ongoing effort to compute the angular momentum of the gluons in the proton.