Isolated Photon Hadron Correlations in √sNN = 5.02 TeV pp and p–Pb Collisions

This work presents the measurement of isolated photon-hadron correlations and the first study of photon-tagged fragmentation in p–Pb at the Large Hadron Collider using pp and p–Pb data collected by the ALICE detector. Prompt photons produced at leading order in hard scatterings constrain the kinematics of the recoiling parton, enabling the study of parton energy loss and modification to the parton fragmentation function. For photons with |η| < 0.67 and 12 < pT < 40 GeV/c, the associated yield of charged particles in the previously unexplored kinematic range of 0.5 < pT < 8 GeV/c is measured. No significant difference between pp and p–Pb is observed. Pythia 8.2 and cold nuclear matter theoretical models can describe both data sets within uncertainties, setting constraints on cold nuclear matter effects on the parton fragmentation in p–Pb collisions.