Interpolative Formulas for Pion-Nucleon Scattering Phase Shifts

Interpolative expiessions for the phase shifts in pi -N interactions in the energy range up to 600 Mev are considered. Each s- and p-wave phase shift is treated individually. The Fermi-type phase shifts found in individual experiments at various energies were taken as the points to be fitted by the interpolative expressions. Polynomial fits with two, three, and six parameters were calculated by a least squares fitting program for the dominant (3,3) phase shift. To indicate the behavior of the phase shift expressions that were obtained, the real parts of the forward scattering amplitudes were calculated and compared with the results of dispersion relation evaluations. (C.E.S.)