The S/sub 11/-P/sub 11/ phase shifts of pion-nucleon scattering

The S/sub 11/ and P/sub 11/ partial amplitude is calculated using the N/D method. The present calculation differs from the previous ones in the handling of the divergent behaviour of the forces due to first- order diagrams, by parametrizing the short-range forces, and in the way of including inelasticity. The nucleon is obtained as a bound state with correct mass and residue and the correct S/sub 11/ and P /sub 11/ scattering lengths. The calculated S-wave and P-wave phase shifts and absorption coefficients are in substantial agreement with those from the CERN theoretical (1970) and Almehed-Lovelace (1972) phase shift analyses. (22 refs).