Eur. Phys. J. A (2021) 57: 22
https://doi.org/10.1140/epja/s10050-020-00330-6

Regular Article – Theoretical Physics

QED effects on the spin asymmetry in elastic ${}^{12}$C($e,e^{\prime }$) collisions

Mathematics Institute, University of Munich, Theresienstrasse 39, 80333, Munich, Germany

^a dj@mathematik.uni-muenchen.de

Received: 16 September 2020
Accepted: 14 December 2020
Published online: 13 January 2021

Abstract

The influence of quantum electrodynamic (QED) effects on the Sherman function S for the scattering of polarized electrons from a ${}^{12}$C nucleus is investigated. While vacuum polarization is treated to all orders via the Uehling potential, the vertex correction, self energy, soft bremsstrahlung and dispersion corrections are accounted for to lowest order within the plane-wave Born approximation. The latter are estimated with the help of a closure approximation. The additional emission of hard bremsstrahlung is calculated by means of the Sommerfeld–Maue theory. Photons up to 4 MeV are included, corresponding to the detector resolution in future experiments. In the collision energy regime considered, 20–180 MeV, the combined QED effects lead to considerable changes in S, amounting to 5–40% at the larger scattering angles.