Two-gluon correlations and initial conditions for small-x evolution

TL;DR

This paper derives an effective action for large-x valence charges, highlighting the importance of non-Gaussian contributions in initial conditions for small-x evolution and their impact on two-gluon correlations.

Contribution

It introduces a fourth-order effective action for valence charges, emphasizing the role of non-Gaussian weight functionals in initial conditions for small-x evolution.

Findings

Non-Gaussian operators contribute at leading order in N_c.

Infrared divergences differ from Gaussian theories, affecting correlations.

Higher-dimensional operators should be included in initial ensembles for JIMWLK evolution.

Abstract

We derive the effective action of the hard large-x valence charges up to fourth order in their density. Such non-Gaussian weight functionals contribute at leading order in N_c to the connected two-gluon production diagrams which determine di-hadron correlations. The corresponding diagrams are not necessarily (highly) suppressed by the density of valence charges since their infrared divergences differ from those obtained in a Gaussian theory. Therefore, it appears prudent to include such higher dimensional operators when determining initial ensembles for JIMWLK evolution of higher n-point functions of Wilson lines.