J/ψ 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 (UPC). Exclusive photoproduction of J/ψ vector mesons is sensitive to the gluon distribution of the interacting target (proton or nucleus). This process is expected to be sensitive to saturation phenomena and nuclear gluon shadowing. Here we report on the ALICE measurement of J/ψ coherent photoproduction in Pb-Pb UPC at sNN=2.76 TeV at forward and central rapidities. Furthermore, we also present results on the J/ψ photoproduction in p-Pb UPC at sNN=5.02 TeV in the forward and backward rapidities, where the rapidity is measured in the laboratory frame with respect to the proton beam direction. The J/ψ mesons have been identified through their leptonic decays.