Measurement of the D-meson nuclear modification factor and elliptic flow in Pb–Pb collisions at √SNN = 5.02 TeV with ALICE at the LHC

Heavy-flavour hadrons are recognised as a powerful probe for the characterisation of the deconfined medium created in heavy-ion collisions, the Quark-Gluon Plasma (QGP). The ALICE Collaboration measured the production of D 0 , D + , D* + and Ds+ mesons in Pb–Pb collisions at SNN = 5.02 TeV. The measurement of the nuclear modification factor ( R AA ) provides a strong evidence of the in-medium parton energy loss. The comparison between the Ds+ and the non-strange D-meson R AA can help to study the hadronisation mechanism of the charm quark in the QGP. In mid-central collisions, the measurement of the D-meson elliptic flow v 2 at low transverse momentum ( p T) gives insight into the participation of the charm quark into the collective motion of the system, while at high p T it constrains the path-length dependence of the energy loss. The Ds+ v 2 , measured for the first time at the LHC, is found to be compatible to that of non-strange D mesons and positive with a significance of about 2.6 σ. The coupling of the charm quark to the light quarks in the underlying medium is further investigated for the first time with the application of the Event-Shape Engineering (ESE) technique to D-meson elliptic flow.