Measurement of prompt D0 and D‾0 meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at sNN=5.02TeV

Abstract The strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity-dependent difference ( Δ v 2 ) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v 2 ) between D 0 ( u ‾ c ) and D ‾ 0 ( u c ‾ ) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Δ v 2 . The rapidity-averaged value is found to be 〈 Δ v 2 〉 = 0.001 ± 0.001 (stat) ± 0.003 (syst) in PbPb collisions at s NN = 5.02 TeV . In addition, the influence of the collision geometry is explored by measuring the D 0 and D ‾ 0 mesons 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.