The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity dependent difference (v2) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v2) between D0 (uc) and D0 (uc) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of v2. The rapidity-averaged value is found to be v2 = 0.001±0.001 (stat)±0.003 (syst) in PbPb collisions at √sNN = 5.02 TeV. In addition, the influence of the collision geometry is explored by measuring the D0 and D0 mesons v2 and triangular flow coefficient (v3) as functions of rapidity, transverse momentum (pT), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D0 meson v2 values is observed, while the v3 is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry.

Individuals have received support from the Marie-Curie program and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 752730, and 765710 (European Union); CERN; the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509 and the Programa Severo Ochoa del Principado de Asturias.

CMS Collaboration: et al.

Peer reviewed