Comparative study of final-state-interaction contributions to the dynamic response of quantum fluids

The expression for the final-state-interaction part of the dynamic response S(q,{ω}), as given by Silver, is derived from a multiple-scattering theory. We first discuss the single-scattering term, which has the same form in the analyses of Silver and Rinat. Next, we indicate the approximations that permit a summation of the full scattering series in the form given by Silver. We argue that under currently prevailing conditions, which include instrumental resolution, the approximated sum for S is dominated by the first two terms.