Measurement of D0-meson production in Pb-Pb and p-Pb collisions with the ALICE experiment at the LHC

Abstract

In this article, a review of the measurements of the production of prompt charmed D0 mesons relative to the reaction plane in Pb-Pb collisions at the centre-of-mass energy per nucleon-nucleon collision of $\sqrt{s_{NN}} = 2.76$ TeV, and of the D0 production in p-Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with the ALICE experiment at the CERN Large Hadron Collider is presented. The azimuthal anisotropy is quantified via the second coefficient v2 in a Fourier expansion of the D0 azimuthal distribution, and the nuclear modification factor $R_{AA}$ , measured with respect to the reaction plane. The D0 production is measured in both systems by reconstructing the two-prong hadronic decay $D^{0} \rightarrow K^{-}\pi^{+}$ in the central rapidity region. A positive elliptic flow is observed in Pb-Pb collisions in the centrality class 30-50%, with a mean value of $0.204^{+0.099}_{-0.036}$ in the interval $2< p_{T} < 6$ GeV/c, which decreases towards more central collisions. Consequently, the nuclear modification factor shows a stronger suppression in the direction orthogonal to the reaction plane. The D0 nuclear modification factor $ R_{pPb}$ in p-Pb collisions is compatible with unity within uncertainties. The multiplicity dependence of the D0 production is also studied by comparing yields in p-Pb collisions in four event classes with those in pp collisions, scaled by the number of binary nucleon-nucleon collisions, as well as by evaluating the yields per event in multiplicity intervals normalised to the multiplicity-integrated ones. The nuclear modification factor is consistent with unity in the four considered event classes, within uncertainties. The relative D0-meson yields increase as a function of the charged-particle multiplicity. The Pb-Pb and p-Pb results are compared to theoretical calculations of charm quark transport and energy loss in high-density strongly interacting matter at high temperature and including initial-state effects induced by the nuclear environment, respectively.