S-wave π-nucleon scattering in the Skyrme model

Although the Skyrme model has enjoyed considerable success in π-nucleon scattering, the s-waves have remained a problem. In this paper we examine s-wave π-nucleon scattering using approximations that, unlike the usual approaches, preserve the soft-pion theorems. When recoil, a large effect, is included, we find no resonances below 1 GeV in either the S11 or S31 partial wave and obtain very good agreement with the experimental data in both partial waves. The Skyrme model calculations are compared with cloudy bag model calculations and, at least for the low-energy s-wave scattering, found to be inferior. This comparison suggests additional terms which will help cure the problems with the Skyrme model calculations. (orig.)