High energy QCD beyond the mean field approximation

TL;DR

This paper reviews recent theoretical advances in high-energy QCD beyond the mean field approximation, emphasizing the roles of fluctuations, Lorentz invariance, and unitarity in understanding scattering processes and saturation phenomena.

Contribution

It summarizes key developments in incorporating gluon number fluctuations and Pomeron loops into high-energy QCD models, extending beyond traditional mean field approaches.

Findings

Inclusion of gluon fluctuations alters the saturation scale.

Discreteness and fluctuations impact scattering amplitude predictions.

Connections between high-energy QCD and statistical physics are elucidated.

Abstract

It has been recently understood how to deal with high-energy scattering beyond the mean field approximation. We review some of the main steps of this theoretical progress, like the role of Lorentz invariance and unitarity requirements, the importance of discreteness and fluctuations of gluon numbers (Pomeron loops), the high-energy QCD/statistical physics correspondence and the consequences for the saturation scale, the scattering amplitude and other, also measurable, quantities.