Some Non-Born Phase Shifts

Abstract

Over the past few years, there have been a number of independent attempts to improve on the Born approximation calculation of scattering phase shifts. The similarity of several of the first-order results for central potentials has led to misconceptions as to their interrelationship. The interpretation of the approximations has now been put on a firm basis (sometimes at variance with the previous literature). The alternatives in going to higher order are sorted out and their meaning is clarified. The extensions to noncentral potentials are given. In addition, a numerical exploration of the precision of different higher order results has been carried out.