Pion electro-production in the Roper region in chiral quark models
Abstract
We present a method to calculate pion electro-production amplitudes in a coupled-channel framework incorporating quasi-bound quark-model states. The method offers a clear prescription how to extract the resonant part of the amplitudes, even in the presence of different decay channels and a strong mixing of neighbouring resonances. The method is applied to the calculation of the M1- and the S1- amplitudes in the P11 partial wave in a simple chiral quark model. A good agreement with the observed M1- amplitude is found with a significant contribution from the pion cloud. The same effect is also prominent in the S1- amplitude but a rather uncertain data prevent us to draw a definitive conclusion.
Keywords
Cite
@article{arxiv.0906.2066,
title = {Pion electro-production in the Roper region in chiral quark models},
author = {B. Golli and S. Sirca and M. Fiolhais},
journal= {arXiv preprint arXiv:0906.2066},
year = {2009}
}
Comments
8 pages, 10 Postscript figures, Fig. 7 and Fig. 8 changed