Measurement of collective flow of D ⁰ mesons in heavy-ion collisions at CMS

The study of heavy quarks provides a powerful tool to probe the transport properties of the quark-gluon plasma (QGP) created in high-energy heavy-ion collisions. In particular, the azimuthal anisotropy coefficients ( v n ) and the nuclear modification factor ( R AA ) serve as sensitive observables to study the dynamics of QGP. We present the measurements of the elliptic ( v 2 ) and triangular ( v 3 ) flow coefficients of prompt and non-prompt D 0 mesons in lead-lead (PbPb) collisions at √ s NN = 5.02 TeV, using the data collected by the CMS experiment. The results are reported as a function of particle’s transverse momentum (p T ) for different centrality intervals. The v 2 coefficient reflects both the collective expansion of the QGP and the path-length dependent energy loss of heavy quarks, whereas v 3 is primarily driven by fluctuations in the initial state geometry and the subsequent medium response. The flow of prompt D 0 mesons provides direct insight into the charm-quark interactions with the medium, while non-prompt D 0 mesons, originating from B hadron decays, offer a unique avenue to study bottom quark dynamics in the QGP. A comparative study of prompt and non-prompt D 0 mesons reveals the mass and flavor dependence of heavy-quark energy loss mechanisms. Confronting these results with theoretical models provides critical constraints on the description of heavyquark transport and the degree of collectivity in the QGP.