Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering

TL;DR

This study investigates how azimuthal asymmetries in deeply virtual Compton scattering vary with nuclear mass, finding no dependence, and compares these asymmetries across different nuclei and a free proton.

Contribution

It provides the first detailed analysis of nuclear-mass dependence of azimuthal asymmetries in DVCS, covering both coherent and incoherent regions.

Findings

No nuclear-mass dependence of asymmetries observed

Asymmetries are consistent across different nuclei and free proton

Results support universality of GPDs across nuclei

Abstract

The nuclear-mass dependence of azimuthal cross section asymmetries with respect to charge and longitudinal polarization of the lepton beam is studiedfor hard exclusive electroproduction of real photons. The observed beam-charge and beam-helicity asymmetries are attributed to the interference between the Bethe-Heitler and deeply virtual Compton scattering processes. For various nuclei, the asymmetries are extracted for both coherent and incoherent-enriched regions, which involve different (combinations of) generalized parton distributions. For both regions, the asymmetries are compared to those for a free proton, and no nuclear-mass dependence is found.