Application of a Unitary Impulse Approximation to Pion-Nucleon Scattering

A unitary impulse approximation given previously is described here in a more general (multichannel) form. To test the method, we apply it to a soluble model of $K^{-}-d$ scattering and obtain encouraging results. The method is then applied to $\pi -N$ elastic scattering. Good agreement with the experimentally determined $d_{13}$ amplitude is obtained for energies near the second resonance. While the impulse approximation violates unitarity bounds, the unitary impulse approximation shows no such violations.