Calculation of the axial charge in the epsilon and epsilon' regimes of HBChPT

TL;DR

This paper develops a new technique within Heavy Baryon Chiral Perturbation Theory to accurately compute the axial charge g_A in the epsilon and epsilon' regimes, including contributions from pion zero modes.

Contribution

It introduces a novel method for calculating baryon properties in the epsilon regime, applicable at arbitrary order and diagram by diagram, enhancing precision in chiral perturbation theory.

Findings

Calculated g_A to order epsilon^3 in the epsilon regime.

Extended the calculation to the epsilon' regime to order epsilon'^3.

Discussed the applicability domains of both regimes.

Abstract

The axial charge g_A is calculated in the epsilon regime of Heavy Baryon Chiral Perturbation Theory to order epsilon^3. To perform this calculation, we develop a technique to compute baryon properties in the epsilon regime of Chiral Perturbation Theory. This technique includes contributions from pion zero momentum modes and can be used at arbitrary order, diagram by diagram, in the $\epsilon$ regime to calculate any matrix element. Also, a calculation of g_A in the epsilon' regime to order epsilon'^3 is performed. A discussion of the domain of applicability for both the epsilon and epsilon' regimes is also included.