Universality of Unintegrated Gluon Distributions at small x

TL;DR

This paper explores the universality of unintegrated gluon distributions at small x, establishing effective factorization and linking different gluon distributions through dijet production processes in high-energy collisions.

Contribution

It demonstrates the direct probing of gluon distributions via dijet correlations and relates various distributions in the large-Nc limit, advancing understanding of gluon universality.

Findings

Weizs"{a}cker-Williams gluon distribution can be probed in DIS dijet correlations.

Dipole gluon distribution measurable in pA photon-jet correlations.

Unintegrated gluon distributions are related in the large-Nc limit.

Abstract

We systematically study dijet production in various processes in the small-$x$ limit and establish an effective $k_t$-factorization for hard processes in a system with dilute probes scattering on a dense target. We find that the well-known Weizs\"{a}cker-Williams gluon distribution can be directly probed in the quark-antiquark jet correlation in deep inelastic scattering and the dipole gluon distribution can be directly measured in the direct photon-jet correlation in $pA$ collisions. In the large-$N_c$ limit, the unintegrated gluon distributions involved in other different dijet channels in pA collisions are shown to be related to two widely proposed ones: the Weizs\"{a}cker-Williams gluon distribution and the dipole gluon distribution.