Nonlocal and Majorana Exchange Terms in the Optical Model

The suggestion that nonlocal terms arising from the effects of antisymmetrization in light systems should be present in heavier systems, is examined. The introduction of one such term into the optical potential for proton-nucleus scattering produces significant effects at backward angles. It is shown that these nonlocal effects can be represented almost exactly by the introduction of a Majorana component into the real central potential. The results are applied in an analysis of 30-MeV proton elastic scattering data from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$.