Glue Spin of the Proton

TL;DR

This paper reports on lattice QCD calculations of the gluon spin contribution to proton spin, showing a mild dependence on the frame and providing an unrenormalized estimate of 0.13(3) at a specific momentum.

Contribution

It presents a new lattice QCD computation of the gluon spin contribution to proton spin using overlap fermions on DWF gauge configurations, with progress on matching and mixing calculations.

Findings

Unrenormalized gluon spin contribution S_G = 0.13(3) at p^2=4 GeV^2

Mild frame dependence observed in the calculations

Progress on matching and mixing with effective field theory

Abstract

We report the progress on the lattice QCD calculation of the glue spin contribution to proton spin. This calculation is carried out with valence overlap fermion on 2+1 flavor DWF gauge configurations at two lattice spacings with the momentum of the frame in the kinematic range $0\leq p^2 \leq 2$ GeV$^2$. A mild frame dependence is observed. The matching and mixing with large-momentum effective field theory are in progress. The unrenormalized result at $p^2=4$ GeV$^2$ with $O(a^2)$ correction gives $S_G$ = 0.13(3).