Abstract
The prompt meson azimuthal anisotropy coefficients, and , are measured at midrapidity () in Pb-Pb collisions at a center-of-mass energy per nucleon pair with data collected by the CMS experiment. The measurement is performed in the transverse momentum () range of 1 to , for central and midcentral collisions. The coefficient is found to be positive throughout the range studied. The first measurement of the prompt meson coefficient is performed, and values up to 0.07 are observed for around . Compared to measurements of charged particles, a similar dependence, but smaller magnitude for , is found for prompt meson and coefficients. The results are consistent with the presence of collective motion of charm quarks at low and a path length dependence of charm quark energy loss at high , thereby providing new constraints on the theoretical description of the interactions between charm quarks and the quark-gluon plasma.
- Received 11 August 2017
- Revised 6 March 2018
DOI:https://doi.org/10.1103/PhysRevLett.120.202301
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© 2018 CERN, for the CMS Collaboration