Fox-Wolfram moment of jet production in relativistic heavy-ion collisions*

Abstract Fox-Wolfram moments (FWMs) are a set of event shape observables that characterize the angular distribution of energy flow in high-energy collisions. In this paper, we present the first theoretical investigation of FWMs for multi-jet production in relativistic heavy-ion collisions. We computed jet productions in p + p collisions using a Monte Carlo event generator called SHERPA. In addition, we used the linear Boltzmann transport model to simulate the multiple scatterings of energetic partons in the hot and dense QCD matter. We also calculated the event-normalized distributions of the lower-order FWM, , in p + p and Pb+Pb collisions. We found that for events with jet number , the distribution in Pb+Pb collisions is suppressed for small regions while it is enhanced for large regions as compared to p + p collisions. For events with , the jet-number reduction effect due to jet quenching in QGP decreases the distribution for large regions in Pb+Pb collisions relative to p + p collisions. The medium modifications of the Fox-Wolfram moment for events with are also presented. They resemble those of events with . This is demonstrated by the relative contribution fractions of events with different final-state jet numbers with respect to .