Medium Modifications of Heavy-Flavor Jet Angularities in High-Energy Nuclear Collisions

Abstract We present the first theoretical study on heavy-flavor jet angularities (${\lambda }_{\alpha }^{\kappa }$) in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The initial production of heavy-flavor jets was carried out using the POWHEG+PYTHIA8 prescription. In contrast, the SHELL transport model describes jet evolution in the quark-gluon plasma (QGP). In p+p collisions, we observed narrower angularity distributions for D⁰-tagged jets than for inclusive jets, consistent with the ALICE preliminary results. We then demonstrate that jet quenching in the QGP slightly widens the angularity distribution of D⁰-tagged jets in Pb+Pb collisions relative to that in p+p collisions for a jet transverse momentum of $10<p_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}<20$ GeV/c. In contrast, the angularity distributions of the inclusive and D⁰-tagged jets become narrower in Pb+Pb collisions relative to p+p at $p_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}>20$ GeV/c because of the strong influence of selection bias. Additionally, by comparing the average angularities $\langle {\lambda }_{\alpha }^{\kappa }\rangle$ of the inclusive, D⁰-tagged, and B⁰-tagged jets with varying α and κ, we show that the larger the quark mass, the lower the jet’s $\langle {\lambda }_{\alpha }^{\kappa }\rangle$ values are. As a result of the slenderer initial distribution, we predict that compared with inclusive jets, heavy-flavor jets, especially B⁰-tagged ones, will suffer stronger modifications of $\langle {\lambda }_{\alpha }^{\kappa }\rangle$ in Pb+Pb relative to p+p at $10<p_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}<20$ GeV/c. For a larger jet radius, a more significant broadening of the jet angularities was predicted because of the enhanced contribution of the wide-angle particles.