Pole structure from energy-dependent and single-energy fits to $\pi N$ elastic scattering data

TL;DR

This paper investigates the pole structure of elastic πN scattering data using energy-dependent and single-energy fits, applying multiple methods to extract pole positions and residues, and compares results with previous analyses.

Contribution

It introduces a comprehensive analysis of pole structures using diverse fitting methods and compares these results with existing data, enhancing understanding of πN scattering.

Findings

Consistent pole positions obtained from different methods.

Comparison shows agreement with previous analyses.

Errors estimated for all extracted parameters.

Abstract

The pole structure of the current GW/SAID partial-wave analysis of elastic $\pi N$ scattering and $\eta N$ production data is studied. Pole positions and residues are extracted from both the energy-dependent and single-energy fits, using two different methods. For the energy-dependent fits, both contour integration and a Laurent+Pietarinen approach are used. In the case of single-energy fits, the Laurent+Pietarinen approach is used. Errors are estimated and the two sets of results are compared to other recent and older fits to data.