Deeply Virtual Compton Scattering Beam-Spin Asymmetries

TL;DR

This paper reports precise measurements of beam spin asymmetries in deeply virtual Compton scattering, providing valuable data to constrain the nucleon's generalized parton distributions in the valence quark region.

Contribution

It presents high-statistics measurements of beam spin asymmetries over a wide kinematic range, supporting leading-twist dominance and aiding GPD modeling.

Findings

Asymmetries are consistent with leading-twist expectations.

Data covers x_B from 0.11 to 0.58, Q^2 from 1 to 4.8 GeV^2.

Results constrain generalized parton distributions.

Abstract

The beam spin asymmetries in the hard exclusive electroproduction of photons on the proton (ep -> epg) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x_B from 0.11 to 0.58, Q^2 from 1 to 4.8 GeV^2, -t from 0.09 to 1.8 GeV^2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A = a*sin(phi)/[1+c*cos(phi)]. This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.