Chiral-odd generalized parton distributions, transversity decomposition of angular momentum, and tensor charges of the nucleon

TL;DR

This paper investigates chiral-odd generalized parton distributions and their moments within the chiral quark soliton model, revealing insights into nucleon spin structure, angular momentum decomposition, and tensor charges, with implications for Boer-Mulders effects.

Contribution

It provides a theoretical analysis of chiral-odd GPDs and their moments, linking them to nucleon angular momentum and tensor charges, and discusses their scale dependence and empirical extraction.

Findings

Strong correlation between quark spin and orbital angular momentum.

Isoscalar dominance of the first moment sum rule.

Tensor charges exhibit significant scale dependence.

Abstract

The forward limit of the chiral-odd generalized parton distributions (GPDs) and their lower moments are investigated within the framework of the chiral quark soliton model (CQSM), with particular emphasis upon the transversity decomposition of nucleon angular momentum proposed by Burkardt. A strong correlation between quark spin and orbital angular momentum inside the nucleon is manifest itself in the derived second moment sum rule within the CQSM, thereby providing with an additional support to the qualitative connection between chiral-odd GPDs and the Boer-Mulders effects. We further confirm isoscalar dominance of the corresponding first moment sum rule, which indicates that the Boer-Mulders functions for the $u$- and $d$-quarks have roughly equal magnitude with the same sign. Also made are some comments on the recent empirical extraction of the tensor charges of the nucleon by Anselmino et al. We demonstrate that a comparison of their result with any theoretical predictions must be done with great care, in consideration of fairly strong scale dependence of tensor charges, especially at lower renormalization scale.