Validity of Neglecting Continuum Contributions in Two-Body Rearrangement Collisions

The neglect of $n$-body breakup contributions, $n>~3$, is a widely used but previously untested approximation occurring in the analysis of almost all atomic, molecular, and nuclear collisions. A simple three-body model of deuteron stripping is used to study this approximation. Below the breakup threshold, use of this approximation accounts for the overall shape of the angular distributions and fits the exact transfer cross section at forward angles. With increasing energies, continuum effects render this approximation much less accurate.