Single--Spin Asymmetries in the Bethe--Heitler Process $e^{-}+p\to e^{-}+\gamma +p$ from QED Radiative Corrections

Abstract

We derived analytic formulae for the polarization single--spin asymmetries (SSA) in the Bethe--Heitler process $e^{-}+p\to e^{-}+\gamma +p$. The asymmetries arise due to one-loop QED radiative corrections to the leptonic part of the interaction and present a systematic correction for the studies of virtual Compton Scattering on a proton through interference with the Bethe-Heitler amplitude. Considered are SSA with either longitudinally polarized electron beam or a polarized proton target. The computed effect appears to be small, not exceeding 0.1 per cent for kinematics of current virtual Compton scattering experiments.

8 pages, 9 figures