Phases of Partial Matrix Elements and the Parity Rule for Inelastic Scattering

Abstract

It is shown that the phases of the partial matrix elements in the distorted-wave Born approximation, which are responsible for effects like forward and backward peaks in angular distributions, are closely related to the elastic scattering phase shifts for the entrance and exit channels and hence largely independent of the particular optical model used to calculate the wave functions. Phase considerations are used to verify the parity rule for even angular momentum transfer, and the conditions under which it is expected to hold are discussed.