Correlation expansion of the optical potential

The multiple scattering theory for the optical potential is examined. This series is arranged according to the number of target particles struck in forming the optical potential. The term which involves two target particles is summed as a three-body problem. Explicit formulas for calculating the optical potential in the fixed scatterer approximation are presented. Corrections to the fixed scatterer approximation, one a correction to closure, another a correction due to nonlocality in the two-body interaction, are presented. The relation between this work and other formal rearrangements of the multiple scattering series is presented.SCATTERING THEORY. Optical potential. Multiple scattering. Nucleon-nucleus scattering.