Prompt photon production and photon-hadron correlations at RHIC and the LHC from the Color Glass Condensate

TL;DR

This paper uses the Color Glass Condensate framework to analyze prompt photon production and photon-hadron correlations in high-energy proton-nucleus collisions, predicting saturation effects and azimuthal correlation suppression at RHIC and LHC.

Contribution

It introduces a detailed CGC-based analysis of prompt photon processes, highlighting the sensitivity to gluon saturation and providing predictions for future collider experiments.

Findings

Direct photon production is more sensitive to gluon saturation effects.

Strong suppression of away-side photon-hadron correlations at forward rapidities.

Predictions for nuclear modification factors at RHIC and LHC.

Abstract

We investigate inclusive prompt photon and semi-inclusive prompt photon-hadron production in high energy proton-nucleus collisions using the Color Glass Condensate (CGC) formalism which incorporates non-linear dynamics of gluon saturation at small x via Balitsky-Kovchegov equation with running coupling. For inclusive prompt photon production, we rewrite the cross-section in terms of direct and fragmentation contributions and show that the direct photon (and isolated prompt photon) production is more sensitive to gluon saturation effects. We then analyze azimuthal correlations in photon-hadron production in high energy proton-nucleus collisions and obtain a strong suppression of the away-side peak in photon-hadron correlations at forward rapidities, similar to the observed mono-jet production in deuteron-gold collisions at forward rapidity at RHIC. We make predictions for the nuclear modification factor R_{p(d)A} and photon-hadron azimuthal correlations in proton(deuteron)-nucleus collisions at RHIC and the LHC at various rapidities.