Off-Shell Effects in Nucleon-Nucleus Scattering

It is shown that the usual multiple-scattering treatment of nucleon-nucleus elastic scattering does not provide a complete description of the process. In particular, the replacement of the two-nucleon interaction potential by a two-body $T$ matrix (evaluated at a single parametric energy) leads to an inadequate treatment of the off-shell aspects of the multiple-scattering problem. As an example, we discuss the manner in which short-range correlations in the nuclear targets affect the off-shell behavior of the two-body scattering operators used to describe nucleon-nucleus scattering. The influence of these off-shell effects on the calculation of total cross sections is discussed.