# Gluon Tomography from Deeply Virtual Compton Scattering at Small-x

## TL;DR

This paper evaluates the DVCS cross section at small-x using the dipole model, revealing azimuthal correlations linked to gluon distributions, and compares results with collinear factorization approaches.

## Contribution

It introduces the calculation of azimuthal angular correlations in DVCS within the dipole framework, including the novel $ ext{cos} 2 ext{phi}$ term from elliptic gluon distributions.

## Key findings

- Identifies $ ext{cos} \, ext{phi}$ and $ ext{cos} 2 ext{phi}$ correlations in DVCS.
- Shows the $ ext{cos} 2 ext{phi}$ term originates from elliptic gluon Wigner distribution.
- Demonstrates consistency with collinear GPD-based approaches.

## Abstract

We present a full evaluation of the deeply virtual Compton scattering (DVCS) cross section in the dipole framework in the small-x region. The result features the $\cos \phi$ and $\cos 2\phi$ azimuthal angular correlations which have been missing in previous studies based on the dipole model. In particular, the $\cos 2\phi$ term is generated by the elliptic gluon Wigner distribution whose measurement at the planned electron-ion collider (EIC) provides an important information about the gluon tomography at small-x. We also show the consistency with the standard collinear factorization approach based on the quark and gluon generalized parton distributions (GPDs).