Medium Effects on Charmonium Production at ultrarelativistic energies   available at the CERN Large Haron Collider
  We investigate with a transport approach the cold and hot nuclear matter effects on the charmonium transverse momentum distributions in relativistic heavy ion collisions. The newly defined nuclear modification factor $r_{AA}=\langle p_{T}^2\rangle_{AA}/\langle p_{T}^2\rangle_{pp}$ and elliptic flow $v_2$ for $J/\psi$ are sensitive to the nature of the hot medium and the thermalization of heavy quarks. From SPS through RHIC to LHC colliding energies, we observe dramatic changes in the centrality dependence of $r_{AA}$. We find that at LHC energy, the finally observed charmonia are dominated by the regeneration from thermalized heavy quarks. 
Kai Zhou, Nu Xu, Zhe Xu and Pengfei Zhuang
nucl-th hep-ex hep-ph nucl-ex