摘要
A coupled-channel approach incorporating quasi-bound quark-model states has been used to calculate pion-nucleon scattering amplitudes in the P11 and S11 partial waves and the corresponding pion electro-production amplitudes. The method allows for the extraction of the resonant part of the amplitudes even in the presence of different decay channels and a strong mixing of neighbouring resonances. We demonstrate the important role of the pion cloud at large distances, as opposed to the short-distance behaviour governed by the quark core.
- 出版日期2011-5