Color Glass Condensate meets High Twist Expansion

TL;DR

This paper bridges the Color Glass Condensate and High-Twist frameworks in QCD, showing how they can be matched through sub-eikonal corrections, with a detailed example in photon production.

Contribution

It demonstrates a consistent matching between CGC and HT formalisms up to twist-4, incorporating sub-eikonal effects and initial- and final-state interactions.

Findings

Established the correspondence between CGC and HT frameworks.

Performed detailed calculations for photon production in proton-nucleus collisions.

Provided a method for unifying dilute-dense QCD dynamics.

Abstract

We establish the correspondence between two well-known frameworks for QCD multiple scattering in nuclear media: the Color Glass Condensate (CGC) and the High-Twist (HT) expansion formalism. We argue that a consistent matching between both frameworks, in their common domain of validity, is achieved by incorporating the sub-eikonal longitudinal momentum phase in the CGC formalism, which mediates the transition between coherent and incoherent scattering. We perform a detailed calculation and analysis of direct photon production in proton-nucleus scattering as a concrete example to establish the matching between HT and CGC up to twist-4, including initial- and final-state interactions, as well as their interferences. The techniques developed in this work can be adapted to other processes in electron-nucleus and proton-nucleus collisions, and they provide a potential avenue for a unified picture of dilute-dense dynamics in nuclear media.