Anisotropy of the semi-classical gluon field of a large nucleus at high energy

TL;DR

This paper investigates the azimuthal anisotropy in the gluon fields of a large nucleus at high energy, showing that fluctuations induce anisotropy and that these features persist under certain resummation techniques, with implications for understanding gluon distributions.

Contribution

It demonstrates that fluctuations cause azimuthal anisotropy in the gluon field configurations and that these anisotropies are preserved under impact parameter dependent JIMWLK resummation.

Findings

Configurations are azimuthally anisotropic due to fluctuations.

Anisotropies are preserved over several units of rapidity.

Computed the first four azimuthal Fourier amplitudes of the dipole S-matrix.

Abstract

The McLerran-Venugopalan model describes a highly boosted hadron/nucleus as a sheet of random color charges which source soft classical Weizs\"acker-Williams gluon fields. We show that due to fluctuations, individual configurations are azimuthally anisotropic. We present initial evidence that impact parameter dependent small-x JIMWLK resummation preserves such anisotropies over several units of rapidity. Finally, we compute the first four azimuthal Fourier amplitudes of the S-matrix of a fundamental dipole in such background fields.