Measurement of nonprompt and prompt D0 azimuthal anisotropy in Pb-Pb collisions at √SNN = 5.02 TeV

Abstract

Heavy quarks are primarily produced via initial hard scatterings, and thus carry information about the early stages of the Quark-Gluon Plasma (QGP). Measurements of the azimuthal anisotropy of the final-state heavy flavor hadrons provide information about the initial collision geometry, its fluctuation, and more importantly, the mass dependence of energy loss in QGP. Due to the larger bottom quark mass as compared to the charm quark mass, separate measurements of charm and bottom hadron azimuthal anisotropy can shed new light on understanding the dependence of the heavy quark and medium interaction. Because of the high branching ratio and large D0 mass, measurements of D0 meson coming from bottom hadron decay (nonprompt D0) can cover a broad kinematic range and be a good proxy of the parent bottom hadrons results. In this talk, we report on the prompt D0 and the first nonprompt D0 measurements of the azimuthal anisotropy elliptic (v2) and triangular (v3) coefficients of nonprompt D0 in PbPb collisions at √SNN = 5.02 TeV. The measurements are performed as functions of transverse momentum pT, in three centrality classes, from central to midcentral collisions. Compared to the prompt D0 results, the nonprompt D0 v2 flow coefficients are systematically lower but have a similar dependence on pT and centrality. A non-zero v3 coefficient of the nonprompt D0 is observed. The obtained results are compared with theoretical predictions. The comparison could provide new constraints on the theoretical description of the interaction between heavy quarks and the medium.