Effects of spinor distortion and density-dependent form factors upon quasifree16O(e→,e′p→)

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 ${}^{16}\mathrm{O}\left(\overrightarrow{e}{,e}^{\prime }\overrightarrow{p}\right)$ reaction at $Q^2=0.8\mathrm{}\hspace{0.5em}(\mathrm{GeV}{/c)}^2$. 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 the p shell. However, both effects are subject to much larger Gordon ambiguities than comparable nonrelativistic calculations.