Measurement of the jet mass and angularities in Pb-Pb collisions at 5.02 TeV with ALICE

Abstract: Jet substructure observables provide powerful tools to search for new physics and test theoretical descriptions of perturbative and non-perturbative processes in QCD. In heavy-ion collisions, jet substructure observables are used to elucidate the structure and dynamics of the quark-gluon plasma. Jet mass is one such observable, which probes the virtuality of hard-scattered partons and their modified fragmentation. Additionally, generalized jet angularities provide a powerful tool for differential measurements of the jet shower and its modification, as two parameters vary the weight of the jet constituents' relative angle and $p_\mathrm{T}$. Previous measurements of the jet mass and jet angularities have shown conflicting differences in comparison with models. To clarify these results, we present new measurements of the jet mass and jet angularities using an identical jet sample. The high-precision tracking system of ALICE enables these measurements over a broad range in $p_\mathrm{T}$, with low-$p_\mathrm{T}$ reach that is unique at the LHC. We report the generalized jet mass and jet angularities using charged-particle tracks in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV. Various jet angularity parameters are investigated for the jet resolution parameter $R = 0.2$. Results are compared to pp collisions and theoretical models.