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

Within the framework of leading power factorization formalism of nonrelativistic quantum chromodynamics, we calculate the jet fragmentation function for high transverse momentum $J/\psi$ production in proton-proton (pp) collisions with center-of-mass energies ranging from $\sqrt{s}=500$ GeV to 13 TeV. The good agreements between theory and experimental data indicate that $J/\psi$ production within a jet is dominated by gluon fragmentation. Such a mechanism can be further tested by the predicted jet transverse momentum and radius dependence of jet fragmentation function. Based on the satisfying description of pp baseline, we carry out the first theoretical investigation on the medium modification of $J/\psi$ production within jets in heavy-ion collisions at the Large Hadron Collider, using a linear Boltzmann transport model coupled with hydrodynamical evolution for the simulation of jet-medium interactions. The consistency with the experimental measurement on nuclear modification factor ($R_{\text{AA}}$) by the CMS collaboration reveals that the gluon energy loss is the driving force for the suppression of $J/\psi$ production in jets. Furthermore, we make predictions for the dependence of $R_{\text{AA}}$ on jet transverse momentum and jet radius, which can be tested in future measurements to further constrain the flavor dependence of jet quenching.