Generalized parton distributions of 3He and the neutron orbital structure

TL;DR

This paper calculates the generalized parton distributions of helium-3 to facilitate neutron structure studies, proposing a method to account for nuclear effects in experimental extraction, highlighting the importance of coherent DVCS.

Contribution

It provides the first detailed calculation of helium-3 GPDs in impulse approximation and introduces a technique to extract neutron GPDs considering nuclear effects.

Findings

Neutron contribution dominates helium-3 GPDs at low momentum transfer.

Proposed method improves neutron GPD extraction accuracy.

Coherent DVCS is crucial for accessing neutron orbital angular momentum.

Abstract

The two leading twist, quark helicity conserving generalized parton distributions (GPDs) of 3He, accessible, for example, in coherent deeply virtual Compton scattering (DVCS), are calculated in impulse approximation (IA). Their sum, at low momentum transfer, is found to be largely dominated by the neutron contribution, so that 3He is very promising for the extraction of the neutron information. Anyway, such an extraction could be not trivial. A technique, able to take into account the nuclear effects included in the IA analysis in the extraction procedure, even at moderate values of the momentum transfer, is proposed. Coherent DVCS arises therefore as a crucial experiment to access, for the first time, the neutron GPDs and the orbital angular momentum of the partons in the neutron.