Effects of spinor distortion and density-dependent form factors upon $^{16}O(\vec{e},e'\vec{p})$

Abstract

We propose an effective current operator for nucleon electromagnetic knockout that incorporates spinor distortion and density-dependent nucleon form factors using an effective momentum approximation. This method can be used in a coordinate-space approach with either relativistic or nonrelativistic optical potentials and overlap functions. We studied these effects for the $^{16}O(\vec{e},e' \vec{p})$ reaction at Q^2 = 0.8 (GeV/c)^2. Spinor distortion substantially enhances the left-right asymmetry while reducing the ratio between sideways and longitudinal recoil polarization for p-shell knockout by about 5% for modest missing momenta. We also find that the density dependence of nucleon form factors suggested by a quark-meson coupling model reduces the polarization ratio further. Much larger effects are obtained for the s-shell than for p-shell. However, both effects are subject to much larger Gordon ambiguities than comparable nonrelativistic calculations.