Energy dependent nuclear suppression from gluon saturation in exclusive vector meson production

We calculate exclusive J/iy photoproduction at high energies in the color glass condensate approach. The results are compared to the center-of-mass energy dependent y + A -> J/iy +A cross sections extracted from measurements in ultraperipheral heavy ion collisions at RHIC and LHC. We predict strong saturation-driven nuclear suppression at high energies, while LHC data prefer even stronger suppression. We explore effects of nucleon shaped fluctuations and show that the most recent measurement of the itidifferential incoherent J/iy cross section prefers large event-by-event fluctuations of the nucleon substructure in heavy nuclei, comparable to that found for a free proton.