TEEC and azimuthal correlations in forward γ-hadron production in proton-proton and proton-lead collisions at LHC

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.