The influence of QED on the Radiative Electron Capture process in Highly Charged Ions

The influence of vacuum polarization on the Sherman function during elastic electron-nucleus scattering

“…Since U e is negative like the nuclear potential, the inclusion of U e leads to an enhancement of both the cross section and the spin asymmetry (in the sense that S is more negative at the backmost angles if U e is included), such that dS > 0 irrespective of Z as long as the collision energy is well below 50 MeV. The enhancement of the cross section and of dS increases monotonically with E kin for moderate energies as is generally expected for the QED effects [9,10]. For the Mott polarimeter operating at 3.5 MeV [2], dS = 0.36%.…”

“…Such calculations were performed for the QED corrections to electronic energy levels (see e.g. [8] for early work), radiative electron capture in ion-atom collisions [9] and radiative recombination in electron-atom collisions [10]. For the latter, the changes in the cross section were of the order of one percent (or below) at electron impact energies of 0.5 − 5 MeV.…”

“…and the differential cross section dσ/dΩ for the elastic scattering of spin-polarized electrons from nuclei is obtained from a phase shift analysis of the scattering states ψ V P (r). In this way the Uehling part U e of the vacuum polarization potential is included to all orders [15,9]. Note that in our approach the electron mass is retained but nuclear recoil effects are neglected.…”

Theoretical calculations for precision polarimetry based on Mott scattering

“…At lowest order, the leading QED corrections are the vacuum polarization and self-energy. For heavy nuclei with a large charge number Z these QED effects cannot be treated perturbatively [13][14][15]. The self-energy and vacuum-polarization contributions, being of the same order in the expansion on the fine-structure constant, are expected to be of the same order of magnitude.…”