Deeply virtual Compton scattering on the neutron with positron beam

TL;DR

This paper discusses the importance of measuring Deeply Virtual Compton Scattering (DVCS) on neutrons using positron beams to better understand nucleon structure through Generalized Parton Distributions (GPDs).

Contribution

It highlights the role of neutron DVCS measurements in flavor decomposition of GPDs and in constraining the GPD E, especially through beam-charge asymmetry experiments.

Findings

Neutron DVCS measurements are crucial for flavor separation of GPDs.

Beam-charge asymmetry can improve understanding of GPD E.

Neutron DVCS complements proton target studies.

Abstract

Measuring DVCS on a neutron target is a necessary step to deepen our understanding of the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). The combination of neutron and proton targets allows to perform a flavor decomposition of the GPDs. Moreover, neutron-DVCS plays a complementary role to DVCS on a transversely polarized proton target in the determination of the GPD $E$, the least known and constrained GPD that enters Ji's angular momentum sum rule. A measurement of the beam-charge asymmetry (BCA) in the $e^{\pm} d\to e^{\pm}n\gamma(p)$ reaction can significantly impact the experimental determination of the real parts of the $E$ and, to a lesser extent, $\widetilde{H}$ GPDs.