Transverse momentum spectra and angular correlations in \(Z/\gamma\)-hadron production in relativistic heavy-ion collisions

We carry out a detailed study of medium modifications on transverse momentum spectra and angular correlations between a large transverse momentum hadron and a \(Z/\gamma\) trigger in relativistic heavy-ion collisions within a perturbative QCD parton model improved by the Sudakov resummation technique. The total energy loss of a hard parton propagating inside the medium is employed to modify the fragmentation function, while the medium-induced transverse momentum broadening is included in the resummation approach, and both of them are related to the jet transport parameter and obtained by the higher-twist formalism. We obtain good agreements with the existing data on transverse momentum and azimuthal angular correlations for the \(Z/\gamma\)-hadron pairs in pp and AA collisions and predict the correlations for the \(\gamma\)-hadron in central PbPb collisions at 5.02 TeV. The numerical analyses for the \(Z/\gamma\)-hadron in central PbPb collisions show that the normalized angular distribution is decorrelated due to the medium-induced transverse momentum broadening; however, the angular correlation is enhanced due to the parton energy loss, namely anti-broadening. The observed modification of the angular correlation is a result of the competition between the broadening and the anti-broadening. This work provides a reliable theoretical tool for a comprehensive and precise study of jet quenching in relativistic heavy-ion collisions.