Flavor dependence of energy-energy correlators

Energy-energy correlators (EECs) within high energy jets serve as a key experimentally accessible quantity to probe the scale and structure of the quark-gluon plasma (QGP) in relativistic heavy-ion collisions. The CMS Collaboration’s first measurement of the modification to the EEC within single inclusive jets in Pb + Pb collisions relative to p + p collisions reveals a significant enhancement at small angles, which may arise from jet transverse momentum p T selection biases due to jet energy loss. We investigate the dependence of jet EECs on the flavor of the initiating parton. The EEC distribution of a gluon jet is broader and the peak of transition from the perturbative to the nonperturbative regime occurs at a larger angle than that of a quark jet. Such flavor dependence leads to the different EECs for γ -jets and single inclusive jets due to their different flavor composition. It is also responsible for a colliding energy dependence of EECs of single inclusive jets at fixed jet energy. We also investigate the impact of flavor composition variation on the p T dependence of the jet EEC. We further propose that a change in the gluon jet fraction in A + A collisions compared to p + p can also contribute to a non-negligible enhancement of the medium modified EEC at small angles. Using the model, we predict the reduction of the gluon jet fraction in A + A collisions and estimate its impact on the EEC.