Parton shower evolution in medium and nuclear modification of photon-tagged jets in Pb+Pb collisions at the LHC

TL;DR

This paper models how medium effects in heavy-ion collisions modify photon-tagged jets at the LHC, combining elastic and radiative energy loss to analyze jet yield, energy imbalance, and azimuthal distributions.

Contribution

It introduces a hybrid transport and perturbative QCD model to study medium modifications of photon-tagged jets, accounting for both elastic and radiative energy loss mechanisms.

Findings

Photon-tagged jet yields are suppressed in central collisions.

Jet energy imbalance increases with medium density.

Jet shape observables are sensitive to transport coefficients.

Abstract

We study the medium modification of jets correlated with large transverse momentum photons at the LHC via a transport and perturbative QCD hybrid model which incorporates the contributions from both elastic collisions and radiative energy loss experienced by the parton showers. Calculations are performed for the modification of the photon-tagged jet yield, the photon-jet energy imbalance, and the azimuthal distribution of away-side jets. The modifications of photon-tagged jets with different $x_T = p_{T, J}/p_{T, \gamma}$ values are studied and they exhibit different centrality and jet cone size dependence due to traversing different medium lengths and density profiles. We further investigate the influence of transverse and longitudinal jet transport coefficients on the nuclear modification of photon-tagged jet production and jet shape observables.