Suppression and azimuthal anisotropy of prompt and nonprompt J/ψ production in PbPb collisions at √sNN = 2.76 TeV

Abstract

The nuclear modification factor \(R_{\mathrm{AA}}\) and the azimuthal anisotropy coefficient \(v_{2}\) of prompt and nonprompt (i.e. those from decays of b hadrons) \({\mathrm{J}}/\psi \) mesons, measured from PbPb and pp collisions at \(\sqrt{{s_{_{\text {NN}}}}} =2.76\) \(\,\mathrm{TeV}\) at the LHC, are reported. The results are presented in several event centrality intervals and several kinematic regions, for transverse momenta \(p_{\mathrm{T}} >6.5\) \(\,{\mathrm{GeV}}/{\mathrm{c}}\) and rapidity \(|{y}|<2.4\), extending down to \(p_{\mathrm{T}} =3\) \(\,{\mathrm{GeV}}/{\mathrm{c}}\) in the \(1.6<|{y}|<2.4\) range. The \(v_{2}\) of prompt \({\mathrm{J}}/\psi \) is found to be nonzero, but with no strong dependence on centrality, rapidity, or \(p_{\mathrm{T}}\) over the full kinematic range studied. The measured \(v_{2}\) of nonprompt \({\mathrm{J}}/\psi \) is consistent with zero. The \(R_{\mathrm{AA}}\) of prompt \({\mathrm{J}}/\psi \) exhibits a suppression that increases from peripheral to central collisions but does not vary strongly as a function of either y or \(p_{\mathrm{T}}\) in the fiducial range. The nonprompt \({\mathrm{J}}/\psi \) \(R_{\mathrm{AA}}\) shows a suppression which becomes stronger as rapidity or \(p_{\mathrm{T}}\) increases. The \(v_{2}\) and \(R_{\mathrm{AA}}\) of open and hidden charm, and of open charm and beauty, are compared.