Insights into the gamma* N -> Delta transition

TL;DR

This paper investigates the gamma* N to Delta transition, revealing insights into hadron shape deformation, the role of quark orbital angular momentum, and the behavior of transition form factors at moderate momentum transfers.

Contribution

It provides a detailed analysis of the gamma* N to Delta transition form factors, emphasizing the importance of quark orbital angular momentum and the slow approach to asymptotic limits.

Findings

Magnetic transition form factor decreases faster than neutron's magnetic form factor.

Nonzero quadrupole ratios indicate quark orbital angular momentum.

Quadrupole ratios approach asymptotic limits slowly.

Abstract

The \gamma* N -> \Delta(1232) transition is a window on hadron shape deformation, the applicability of perturbative QCD at moderate momentum transfers, and the influence of nonperturbative phenomena on hadronic observables. We explain that the Ash-convention magnetic transition form factor must fall faster than the neutron's magnetic form factor and nonzero values for the associated quadrupole ratios reveal the impact of quark orbital angular momentum within the nucleon and \Delta(1232); and show that these quadrupole ratios do approach their predicted asymptotic limits, albeit slowly.