Radiative corrections to the spin asymmetry in elastic polarized electron-nucleus collisions at high energy

Abstract

Modifying the numerical codes, dispersion corrections to the beam-normal spin asymmetry which arise from low-lying transient nuclear excitations up to 30 MeV, are estimated for collision energies between 50 MeV and 1 GeV. A nonperturbative calculation of vacuum polarization and the vertex plus self-energy correction, using optimized potentials, indicates that for small scattering angles both these quantum electrodynamical (QED) effects on the spin asymmetry decrease with energy above 200 MeV and can be neglected at high energies. Examples are given for the 12C and 208Pb nuclei. The available measurements of the spin asymmetry at collision energies beyond 500 MeV cannot be explained by the present theory.