Quarkonia suppression in PbPb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV

Abstract

We estimate the modification of quarkonia yields due to different processes in the medium produced in Pb+Pb collisions at LHC energy. The quarkonia and heavy flavour cross sections calculated up to next-to-leading order (NLO) are used in the study. Shadowing corrections are obtained with the NLO EPS09 parametrization. A kinetic model is employed which incorporates quarkonia suppression inside a QGP, suppression due to hadronic comovers, and regeneration from charm pairs. The quarkonia dissociation cross section due to gluon collisions has been considered and the regeneration rate has been obtained using the principle of detailed balance. The modification in quarkonia yields due to collisions with hadronic comovers has been estimated assuming that the comovers are pions. The manifestations of these effects on the nuclear modification factors for both $J/\psi$ and $\Upsilon$ in different kinematic regions has been demonstrated for Pb+Pb collisions at $\sqrt{s_{_{NN}}}$ = 2.76 TeV in comparison with the measurements. Both the suppression and regeneration due to a deconfined medium strongly affect the low and intermediate $p_T$ range. The large observed suppression of $J/\psi$ at $p_T~>$ 10 GeV/$c$ exceeds the estimates of suppression by gluon dissociation.