Isospin violation in low-energy pion-nucleon scattering revisited

TL;DR

This paper revisits isospin violation in low-energy pion-nucleon scattering using covariant baryon chiral perturbation theory, incorporating quark mass differences and electromagnetic effects to analyze the energy dependence of related scattering relations.

Contribution

It provides a comprehensive calculation of isospin breaking effects in pion-nucleon scattering, including electromagnetic corrections, within a covariant chiral perturbation theory framework.

Findings

Quantifies isospin violation effects near threshold.

Analyzes energy dependence of the triangle relation.

Incorporates quark mass differences and photon effects.

Abstract

We calculate isospin breaking in pion-nucleon scattering in the threshold region in the framework of covariant baryon chiral perturbation theory. All effects due to quark mass differences as well as real and virtual photons are consistently included. As an application, we discuss the energy dependence of the triangle relation that connects elastic scattering on the proton pi+- p --> pi+- p with the charge exchange reaction pi- p --> pi0 n.