High Energy QCD at NLO: from light-cone wave function to JIMWLK evolution

TL;DR

This paper derives the JIMWLK Hamiltonian at NLO by computing the soft components of a fast hadron's light-cone wave function up to third order in QCD, incorporating non-linear effects and dense target interactions.

Contribution

It provides a new direct derivation of the NLO JIMWLK Hamiltonian from light-cone wave function calculations in high energy QCD.

Findings

Derived the NLO JIMWLK Hamiltonian from first principles.

Included multi-gluon and quark-antiquark states in the wave function.

Accounted for non-linear density effects in the projectile.

Abstract

Soft components of the light cone wave-function of a fast moving projectile hadron is computed in perturbation theory to third order in QCD coupling constant. At this order, the Fock space of the soft modes consists of one-gluon, two-gluon, and a quark-antiquark states. The hard component of the wave-function acts as a non-Abelian background field for the soft modes and is represented by a valence charge distribution that accounts for non-linear density effects in the projectile. When scattered off a dense target, the diagonal element of the S-matrix reveals the Hamiltonian of high energy evolution, the JIMWLK Hamiltonian. This way we provide a new direct derivation of the JIMWLK Hamiltonian at the Next-to-Leading Order.