Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target

TL;DR

This paper reports comprehensive measurements of single and double spin asymmetries in deeply virtual Compton scattering on a polarized proton, providing new insights into the charge distributions of valence quarks.

Contribution

It presents the first wide kinematic range measurements of DVCS asymmetries with polarized targets, enabling quasi-model-independent extraction of key Compton Form Factors.

Findings

Measured asymmetries cover the widest kinematic range to date.

Extracted imaginary parts of H and H-tilde form factors.

Results agree with some GPD models, constraining proton structure theories.

Abstract

Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton $\vec{e}\vec{p} \to e' p'\gamma$ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized ${}^{14}$NH$_3$ target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. The measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the $H$ and $\tilde{H}$ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.