Calculation of the axial-vector coupling constant $g_A$ to two loops in covariant chiral perturbation theory

TL;DR

This paper calculates two-loop corrections to the axial-vector coupling constant $g_A$ using covariant baryon chiral perturbation theory, showing these corrections are moderate and based on low-energy constants from pion-nucleon scattering.

Contribution

It provides the first detailed two-loop calculation of $g_A$ in covariant chiral perturbation theory with updated low-energy constants.

Findings

Two-loop corrections to $g_A$ are moderate

Low-energy constants from pion-nucleon scattering are used

Results improve understanding of chiral perturbation theory predictions

Abstract

We present a calculation of the leading two-loop corrections to the axial-vector coupling constant $g_A$ in two covariant versions of two-flavor baryon chiral perturbation theory. Taking the low-energy constants from a combined analysis of elastic and inelastic pion-nucleon scattering, we find that these corrections are rather moderate.