# Extracting the sigma-term from low-energy pion-nucleon scattering

## TL;DR

This paper extracts the pion-nucleon sigma-term from low-energy scattering data using Roy-Steiner equations, confirming a large sigma-term value consistent with pionic atom measurements and analyzing uncertainties.

## Contribution

It introduces a novel extraction method of the sigma-term from scattering data, validating previous pionic atom results with detailed stability analysis.

## Key findings

- Sigma-term value of 58(5) MeV confirmed
- Results agree with pionic atom determinations
- Analysis of electromagnetic and normalization uncertainties

## Abstract

We present an extraction of the pion-nucleon ($\pi N$) scattering lengths from low-energy $\pi N$ scattering, by fitting a representation based on Roy-Steiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large $\pi N$ $\sigma$-term, $\sigma_{\pi N}=58(5)$ MeV, in agreement with, albeit less precise than, the determination from pionic atoms.