TEEC and azimuthal correlations in forward {\gamma}-hadron production in proton-proton and proton-lead collisions at LHC

TL;DR

This paper studies photon-hadron correlations in forward rapidity regions for proton-proton and proton-lead collisions at the LHC using the Color Glass Condensate framework, predicting measurable differences relevant for upcoming detector upgrades.

Contribution

It provides the first predictions of TEEC and azimuthal correlations in the small x saturation formalism for forward photon-hadron production at the LHC, including effects of parton shower and hadronization.

Findings

Significant difference in normalized TEECs between proton-proton and proton-lead collisions.

Substantial suppression of azimuthal $b$-hadron correlations in proton-lead collisions.

Predictions are relevant for upcoming detector upgrades with extended pseudorapidity coverage.

Abstract

We investigate photon-hadron Transverse Energy-Energy Correlation (TEEC) and azimuthal correlations in the forward rapidity region for proton-proton and proton-lead collisions within the small $x$ saturation formalism based on the Color Glass Condensate (CGC), supplemented by the initial-state and final-state parton shower simulation and hadronization using CASCADE. The study was performed in light of the upcoming FoCal detector of ALICE and the ATLAS detector upgrades with the extended pseudorapidity coverage. We predict a significant difference, at hadron-level, between the normalized TEECs in proton-proton and proton-lead collisions. Having a direct access to partonic subprocesses we also directly investigate the impact of the parton shower and hadronization on the TEEC. The ordinary azimuthal $\gamma$-hadron correlations show substantial suppression for proton-lead collision, as predicted earlier at parton-level.