Low-Energy Pion-Nucleon Scattering Phase Shifts

Low-energy pion-nucleon scattering phase shifts have been calculated using a model which includes only $N$, $N^{*}$, $\rho$, and $\epsilon$ intermediate states. This remarkably simple model yields good agreement with phase shifts determined from experimental data. There are two adjustable parameters in the model. The even $s$-wave scattering length fixes one of these, and the other is determined by the $\rho$-nucleon magnetic moment coupling. The phase shifts are not sensitive to the choice of this coupling.