부산대학교 도서관

Taking into account the gluon shadowing and the $J/\psi$ nuclear absorption, we evaluate the Cold Nuclear Matter (CNM) effects on $J/\psi$ production in $p$Pb and PbPb collisions at the design LHC energy for PbPb collisions, $\sqrt{s_{NN}}=5.5$ TeV. In view of the good agreement between the yield prediction using the LO CSM and the ALICE data at 7 TeV, we employ the latter model to use a complete description of the kinematics of the underlying $2 \rightarrow 2$ partonic process, namely $g + g \rightarrow J/\psi + g$. We observe a large $J/\psi$ suppression in $p$Pb and PbPb collisions due to the strong shadowing of the gluon distribution in the lead ion at the corresponding gluon momentum fractions. This suppression from CNM effects has a strong rapidity dependence which may compensate, partially or completely, that of of the predicted charm recombination in PbPb collisions.
Comment: 4 pages, 2 figures, talk given by N. Matagne at the conference "ICPAQGP-2010", Goa, India, 6-10 December 2010, submitted to Nuclear Physics A