Measurement of collective flow of D⁰ mesons in heavy-ion collisions at CMS

Indian Institute of Technology Madras, India

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Published online: 5 November 2025

Abstract

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 (v₂) and triangular (v₃) flow coefficients of prompt and non-prompt D⁰ 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 v₂ coefficient reflects both the collective expansion of the QGP and the path-length dependent energy loss of heavy quarks, whereas v₃ is primarily driven by fluctuations in the initial state geometry and the subsequent medium response. The flow of prompt D⁰ mesons provides direct insight into the charm-quark interactions with the medium, while non-prompt D⁰ 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 D⁰ 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.