<i>J/ψ</i> production within a jet in high-energy proton-proton and nucleus-nucleus collisions

We report a systematic study of J /ψ production within a jet in pp and its modification in heavy-ion collisions. Within the framework of leading power factorization formalism of nonrelativistic QCD, we calculate the jet fragmentation function for high- p T J /ψ production in proton-proton collisions. The good agreements between theory and experimental data indicate that J /ψ production within a jet is dominated by gluon fragmentation. And then, we carry out the first theoretical investigation on the medium modification of J /ψ production within jets in heavy-ion collisions, using a linear Boltzmann transport model coupled with hydrodynamical evolution for the simulation of jet-medium interactions. The result reveals that the gluon energy loss is the driving force for the suppression of J /ψ production in jets. Furthermore, we make predictions for the dependence of R AA on jet transverse momentum and jet radius.