$J/\psi$ photoproduction in ultra-peripheral Pb-Pb and p-Pb collisions with the ALICE detector

Ultra-relativistic heavy ions generate strong electromagnetic fields which offer the possibility to study gamma-gamma, gamma-nucleus and gamma-proton processes at the LHC in ultra-peripheral Pb-Pb and p-Pb collisions. Exclusive photoproduction of J/psi vector mesons is sensitive to the gluon distribution of the target. Here we report on the ALICE measurement of J/psi coherent photoproduction in Pb-Pb ultra-peripheral collisions at s**(1/2)_NN = 2.76 TeV for the rapidity ranges -3.6 < y < -2.6 and |y| < 0.9, and on preliminary results on the J/psi photoproduction in p-Pb at s**(1/2)_NN = 5.02 TeV. The J/psi mesons have been identified through their leptonic decays.