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

Improving the numerical precision, dispersion corrections to the beam-normal spin asymmetry which arise from the dominant nuclear excitations, are estimated up to a collision energy of 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 mostly be neglected at high energies. Examples are given for the 12C and 208Pb nuclei. While our results disagree with the measured high-energy spin asymmetry for 12C, they are able to explain the data on 208Pb near 1 GeV.