Jülich-Bonn-Washington Model for Pion Electroproduction Multipoles

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 $1.13\mathrm{GeV}<W<1.6\mathrm{GeV}$ and $Q^2$ below $6{\mathrm{GeV}}^2$ are included. The model is an extension of the latest Jülich-Bonn solution incorporating constraints from pion-induced and photoproduction data. Performing large scale fits ($\sim 10^5$ data) we find a set of solutions with ${\chi }_{\mathrm{dof}}^2=1.69-1.81$ which allows us to assess the systematic uncertainty of the approach.

27 pages, 14 figures