Nuclear shadowing from exclusive quarkonium photoproduction at the BNL   RHIC and CERN LHC
  The photonuclear production of vector mesons in ultraperipheral heavy ion collisions is investigated within the collinear approach using different parameterizations for the nuclear gluon distribution. The integrated cross section and the rapidity distribution for the $AA \to V AA$ ($V = J/\Psi, \Upsilon$) process are computed for energies of RHIC and LHC. A comparison with the recent PHENIX data on coherent production of $J/\Psi$ mesons is also presented. We demonstrate that the study of the exclusive quarkonium photoproduction can be used to constrain the nuclear effects in the gluon distribution. 
A. L. Ayala Filho, V. P. Goncalves, M. T. Griep