Pion scattering and electro-production on nucleons in the resonance region in chiral quark models

TL;DR

This paper models pion scattering and electro-production on nucleons using a chiral quark model framework, successfully describing various resonances and emphasizing the meson cloud's significant role in electromagnetic processes.

Contribution

It introduces a coupled-channel approach with the Cloudy Bag model to comprehensively analyze nucleon resonances and meson cloud effects in scattering and electro-production.

Findings

Accurate description of low-lying nucleon resonances

Meson cloud significantly influences electro-magnetic observables

Consistent results across elastic and inelastic channels

Abstract

Pion scattering and electro-production amplitudes have been computed in a coupled-channel framework incorporating quasi-bound quark-model states, based on the Cloudy Bag model. All relevant low-lying nucleon resonances in the P33, P11, and S11 partial waves have been covered, including the Delta(1232), the N*(1440), N*(1535), and N*(1650). Consistent results have been obtained for elastic and inelastic scattering (two-pion, eta-N, and K-Lambda channels), as well as for electro-production. The meson cloud has been shown to play a major role, in particular in electro-magnetic observables in the P33 and P11 channels.