Suppression and azimuthal anisotropy of prompt and nonprompt J/psi production in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

TL;DR

This study measures the nuclear modification factor and azimuthal anisotropy of prompt and nonprompt J/psi mesons in PbPb collisions at 2.76 TeV, revealing suppression patterns and flow characteristics across different collision centralities and kinematic regions.

Contribution

It provides the first detailed measurements of RAA and v2 for prompt and nonprompt J/psi mesons at this energy, highlighting differences in suppression and flow between charm and beauty decays.

Findings

Prompt J/psi v2 is nonzero but independent of centrality, rapidity, and pt.

Nonprompt J/psi v2 is consistent with zero.

Prompt J/psi suppression increases with collision centrality.

Abstract

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