Saskawa Theory of Reactions

An iterative nonrelativistic theory of reactions is discussed. It generalizes Sasakawa's theory of elastic scattering, published in 1963. A key feature of the theory is its use of zero-order wave functions that allow self-consistent treatment of the asymptotic boundary conditions. This allows the theory to be applied both for inelastic scattering and for rearrangement. The analysis of rearrangement is a special case of the work by Efimenko, Zakhariev, and Zhigunov. The present paper emphasizes a zero-order wave function based on the "surface-$\delta$ model" of channel coupling. This wave function gives a zero-order theory (no iteration) that has the nature of a renormalized distorted-wave Born approximation. This zero-order theory may be adequate for most applications in nuclear physics.