Comparison of theR-Matrix Nuclear Reaction Theories

Abstract
A number of reaction theories are tested and compared by their application to a simple model of s-wave scattering from a two-state nucleus. These theories include the extended R-matrix theory of Garside and Tobocman, the L-operator formalism of Lane and Robson, and variations of the Brown-de Dominicis theory. We find that the Hüfner-Lemmer version of the Brown-de Dominicis theory gives the best results in the few-level approximation.