Numerical Analysis of the Quark Fraction of the Proton Spin

TL;DR

This paper presents a lattice QCD simulation estimating the quark spin contribution to the proton spin, suggesting it is small, aligning with experimental findings that quark spins account for little of the proton's total spin.

Contribution

It provides a lattice QCD-based estimate of the quark spin fraction of the proton, offering theoretical support for experimental results.

Findings

Quark spin fraction of the proton is small.

Results agree with EMC experiment interpretations.

Supports the view that quark spins contribute minimally to proton spin.

Abstract

We report on a lattice QCD estimate of the quark spin fraction of the proton spin. The estimate is arrived at by means of a lattice QCD simulation of the polarized proton matrix element of the Adler-Bell-Jackiw anomaly. The preliminary result of the simulation is that this fraction is rather small. This is in accord with the interpretation of the EMC experiment that the quark spins are responsible for very little, if any, of the proton spin. (Talk given at the Adriatico Research Conference on Polarization Dynamics in Nuclear and Particle Physics, Trieste, January, 1992) NOTE: This paper is available only in postscript form.