Convergence of the chiral expansion for the nucleon mass

TL;DR

This paper investigates the convergence of chiral perturbation theory for the nucleon mass, showing that including fifth-order terms disrupts the previously successful fourth-order extrapolations of lattice data.

Contribution

It demonstrates that fifth-order terms in chiral perturbation theory hinder the convergence for nucleon mass extrapolations, challenging previous assumptions of their reliability.

Findings

Fourth-order chiral perturbation theory successfully extrapolates lattice data.

Inclusion of fifth-order terms worsens the agreement with lattice data.

Convergence issues arise when extending to higher orders in the chiral expansion.

Abstract

A number of papers recently have used fourth-order chiral perturbation theory to extrapolate lattice data for the nucleon mass; the process seems surprisingly successful even for large pion masses. This paper shows that the inclusion of the fifth-order terms spoils the agreement.