Deeply Virtual Compton Scattering off the neutron

TL;DR

This paper reports an experiment measuring the interference effects in Deeply Virtual Compton Scattering off the neutron to extract information about generalized parton distributions and quark contributions to nucleon spin.

Contribution

It introduces a novel experimental approach to extract the imaginary part of DVCS amplitudes on the neutron and deuteron, providing new insights into GPDs and nucleon spin structure.

Findings

Extraction of the imaginary part of DVCS amplitudes on the neutron.

Constraints on the contribution of up and down quarks to nucleon spin.

Sensitivity to the GPD E_q.

Abstract

The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\vec e},e'\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.