The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep⃗ →e′pγ. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sin ϕ moment is 0.252±0.042stat±0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H˜ and H.
Physical Review Letters
Chen, S.; Biselli, Angela; and CLAS Collaboration, "Measurement of deeply virtual compton scattering with a polarized-proton target" (2006). Physics Faculty Publications. 24.
Chen, S., et al. "Measurement of deeply virtual compton scattering with a polarized-proton target." Physical review letters 97.7 (2006): 072002. DOI: 10.1103/PhysRevLett.97.072002