Deeply Virtual Compton Scattering off Polarized and Unpolarized Protons at Hermes

HERMES has measured asymmetries in hard exclusive leptoproduction of real photons from unpolarized and from longitudinally and transversely polarized hydrogen targets in the years 1996-2007. Data on the combined dependence of the cross section on beam helicity and beam charge were analyzed. Sizable asymmetries arise from the Bethe-Heitler process and from the interference with deeply virtual Compton scattering. The measured azimuthal asymmetries are Fourier decomposed and compared to predictions from models of Generalized Parton Distributions. The HERMES recoil detector that was installed in 2006-07 is used to separate exclusive DVCS processes from semi-inclusive processes and from associated DVCS processes.