Hidden-charm Pentaquark States in Heavy Ion Collisions at the Large   Hadron Collider
  In the framework of the quark combination, we derive the yield formulas and study the yield ratios of the hidden-charm pentaquark states in ultra-relativistic heavy ion collisions. We propose some interesting yield ratios which clearly exhibit the production relationships between different hidden-charm pentaquark states. We show how to employ a specific quark combination model to evaluate the yields of exotic $P_c^+(4380)$, $P_c^+(4450)$ and their partners on the basis of reproducing the yields of normal identified hadrons, and execute the calculations in central Pb+Pb collisions at $\sqrt{s_{NN}}= 2.76$ TeV as an example. 
Rui-Qin Wang, Jun Song, Kai-Jia Sun, Lie-Wen Chen, Gang Li, Feng-Lan   Shao
hep-ph nucl-ex nucl-th