On the size of gluon occupancies in saturation

TL;DR

This paper evaluates the size of gluon occupancies in saturation, showing that Sudakov effects impose a maximum size and that saturated gluons exhibit minimal interaction, with implications for understanding gluon distributions in high-energy QCD.

Contribution

It provides a detailed analysis of gluon occupancy sizes in saturation, incorporating Sudakov effects and comparing fixed and running coupling dynamics, revealing minimal interactions among saturated gluons.

Findings

Sudakov effects set a maximum gluon occupancy size of (1/α)^{3/2}.

Gluon TMDs are identical in the saturation region for coherent and inelastic cases.

Saturated gluons appear to have little or no mutual interaction.

Abstract

The size of gluon occupancies, or equivalently the nuclear gluon TMD, at gluon transverse momentum $k_\perp \le Q_s(Y)$ is evaluated. Without Sudakov corrections the occupations can become arbitrarily large while Sudakov effects lead to maximum occupancies of size $(1/\alpha)^{3/2}$. Results are the same for running coupling and fixed coupling dynamics. The coherent (elastic) TMD and inelastic gluon TMD are the same in the gluon saturation region. The saturated gluons in the light cone wavefunction seem to have little or no interaction among themselves.