Initial state azimuthal anisotropies in small collision systems

TL;DR

This paper investigates the origins of azimuthal anisotropies in small collision systems, analyzing how classical color field structures and Wilson line distributions contribute to observed multiparticle correlations in high energy proton-nucleus collisions.

Contribution

It presents new calculations of azimuthal anisotropy coefficients using Wilson line distributions and compares different models, highlighting the impact of quantum evolution on these correlations.

Findings

Wilson line distributions differ significantly between MV model and JIMWLK evolution.

Calculated anisotropy coefficients show notable differences depending on the model used.

The work connects classical field effects with observed multiparticle azimuthal correlations.

Abstract

Strong multiparticle azimuthal correlations have recently been observed in high energy proton-nucleus collisions. While final state collective effects can be responsible for many of the observations, the domain structure in the classical color field of a high energy nucleus also naturally leads to such correlations. We describe recent calculations of the momentum space 2-particle cumulant azimuthal anisotropy coefficients v_n{2}, n=2,3,4 from fundamental representation Wilson line distributions describing the high energy nucleus. We find significant differences between Wilson lines from the MV model and from JIMWLK evolution. We also discuss the relation of this calculation to earlier work on the ridge correlation obtained in the "glasma graph" approximation, and to the "color electric field domain model."