J\"ulich-Bonn-Washington Model for Pion Electroproduction Multipoles

TL;DR

This paper introduces a new, comprehensive model for pion electroproduction off protons, integrating various data types and constraints to improve understanding of nucleon resonance phenomena.

Contribution

It extends the Jülich-Bonn model by incorporating gauge invariance and threshold constraints, fitting extensive data sets to quantify systematic uncertainties.

Findings

Achieved a good fit with $ ext{chi}^2_{ ext{dof}}$ between 1.69 and 1.81

Provided a systematic uncertainty assessment for the model

Extended the model to include a broad energy and momentum transfer range

Abstract

Pion electroproduction off the proton is analyzed in a new framework based on a general parametrization of transition amplitudes, including constraints from gauge invariance and threshold behavior. Data with energies $1.13~{\rm GeV}<W<1.6~{\rm GeV}$ and $Q^2$ below $6~{\rm GeV}^2$ are included. The model is an extension of the latest J\"ulich-Bonn solution incorporating constraints from pion-induced and photoproduction data. Performing large scale fits ($\sim10^5$ data) we find a set of solutions with $\chi^2_{\rm dof}=1.69-1.81$ which allows us to assess the systematic uncertainty of the approach.