Measurement of $J/\psi$ production in 5.02 TeV Pb+Pb collisions with the ATLAS experiment

The in-medium suppression of $J/\psi$ production in heavy-ion collisions, with respect to pp collisions, serves as a sensitive probe for studying the quark gluon plasma. A full assessment of the suppression requires understanding effects present in the hot and dense medium in the Pb+Pb collisions as well as cold nuclear effects in the small p+Pb collision. Based on Pb+Pb collision data collected in 2015 at the LHC, the ATLAS experiment has studied $J/\psi$ production via the dimuon decay channel. The charmonium states are separated into contributions from B-hadron decays and prompt production.