Nucleon spin structure at very high-x

TL;DR

This paper uses Dyson-Schwinger equations to explore the nucleon spin structure at very high momentum fractions, proposing simple formulas for spin-dependent quark distributions and emphasizing the importance of experimental measurements at x=1.

Contribution

It introduces a novel approach linking diquark correlations with nucleon spin structure, providing formulas to predict spin asymmetries at x=1, aiding in distinguishing nucleon models.

Findings

Diquark correlations naturally emerge from dynamical chiral symmetry breaking.

Simple formulas for spin-dependent u- and d-quark ratios at x=1 are derived.

Experimental measurements at x=1 can effectively discriminate between nucleon structure models.

Abstract

Dyson-Schwinger equation treatments of the strong interaction show that the presence and importance of nonpointlike diquark correlations within the nucleon are a natural consequence of dynamical chiral symmetry breaking. Using this foundation, we deduce a collection of simple formulae, expressed in terms of diquark appearance and mixing probabilities, from which one may compute ratios of longitudinal-spin-dependent u- and d-quark parton distribution functions on the domain x =1. A comparison with predictions from other approaches plus a consideration of extant and planned experiments shows that the measurement of nucleon longitudinal spin asymmetries on x =1 can add considerably to our capacity for discriminating between contemporary pictures of nucleon structure.