Measurement of prompt D0 and D0 meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at √sNN = 5.02 TeV

The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity-dependent difference (Δv ₂) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v ₂) between D ⁰ (u‾c) and D‾ ⁰ (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 Δv ₂. The rapidity-averaged value is found to be 〈Δv ₂〉=0.001±0.001(stat)±0.003(syst) in PbPb collisions at s _NN =5.02TeV. In addition, the influence of the collision geometry is explored by measuring the D ⁰ and D‾ ⁰mesons v ₂ and triangular flow coefficient (v ₃) as functions of rapidity, transverse momentum (p _T), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D ⁰ meson v ₂ values is observed, while the v ₃ is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry.