Electroweak Single Pion Production and Form Factors of the \Delta(1232) Resonance

TL;DR

This paper analyzes the electroweak form factors of the 232 resonance, providing new fits to electron and neutrino scattering data, revealing model dependence and refining parameters like axial mass and form factors.

Contribution

It introduces a new fit of the 232 vector form factors based on electron scattering data, highlighting model dependence and updating axial form factor parameters.

Findings

New 232 vector form factor fit from electron scattering data.

Extracted axial mass M_{A232}=0.85^{+0.09}_{-0.08} GeV.

Determined C_5^A(0)=1.10^{+0.15}_{-0.14} consistent with Goldberger-Treiman relation.

Abstract

We extend and review our analysis of the nucleon \to \Delta(1232) transition electroweak form factors from Ref. [1]. New fit of the \Delta(1232) vector form factors to electron-proton scattering F_2 structure function is introduced as well, leading to results different from the popular parametrization of Ref. [2]. A clear model dependence of the extracted parameters emerges. Fit to neutrino scattering data is performed in all available isospin channels. The resulting axial mass is M_{A\Delta}=0.85^{+0.09}_{-0.08} (GeV) and $C_5^A(0) = 1.10^{+0.15}_{-0.14}. The latter value is in accordance with Goldberger-Treiman relation as long as the deuteron effects are included.