Measurement of jet mass in PbPb and pp collisions at 5.02 TeV using ATLAS

The mass of inclusive jets in lead-lead and proton-proton collisions at psNN = 5.02 TeV is reported using the ATLAS detector at the LHC. The measurement of the jet structure in proton-proton collisions is sensitive to the angular and momentum correlations of the jet fragments. It can be used to study modifications of jets in heavy ion collisions where it provides complementary information to previously measured jet fragmentation functions. The mass scaled by the jet transverse momentum of anti-kt R = 0.4 jets is measured as a function of centrality and jet transverse momentum in Pb+Pb collisions and compared to measurements at the same collision energy in proton-proton collisions. The nuclear modification factor is evaluated as a function of the jet mass divided by its transverse momentum as a function of the jet transverse momentum and centrality. No significant dependence of the nuclear modification factor on the mass is observed.