Proton Spin Based On Chiral Dynamics

TL;DR

This paper examines how chiral dynamics models of proton spin align with experimental data, highlighting the importance of the nature of quark-Goldstone boson couplings and their impact on the spin structure.

Contribution

It demonstrates that axial-vector couplings with constituent quarks are incompatible with proton spin data, emphasizing the role of chiral symmetry in spin models.

Findings

Pure spin-flip couplings match experimental data for massless quarks.

Axial-vector couplings with constituent quarks are inconsistent with data.

Chiral models must consider the quark mass and coupling nature to accurately describe proton spin.

Abstract

Chiral spin fraction models agree with the proton spin data only when the chiral quark-Goldstone boson couplings are pure spinflip. For axial-vector coupling from soft-pion physics this is true for massless quarks but not for constituent quarks. Axial-vector quark-Goldstone boson couplings with {\bf constituent} quarks are found to be inconsistent with the proton spin data.