# Coherent photoproduction of $J/\psi$ in nucleus-nucleus collisions in the color dipole approach

Łuszczak, Agnieszka (T. Kościuszko Cracow University of Technology, PL-30-067 Cracow, Poland) ; Schäfer, Wolfgang (Institute of Nuclear Physics Polish Academy of Sciences, ulica Radzikowskiego 152, PL-31-342 Cracow, Poland)

09 April 2019

Abstract: We investigate the exclusive photoproduction of $J/\psi$ mesons in ultraperipheral heavy-ion collisions in the color dipole approach. We first test a number of dipole cross sections fitted to inclusive ${F}_{2}$ data against the total cross section of exclusive $J/\psi$ production on the free nucleon. We then use the color dipole formulation of Glauber-Gribov theory to calculate the diffractive amplitude on the nuclear target. The real part of the free-nucleon amplitude is taken into account consistent with the rules of Glauber theory. We compare our results to recent published and preliminary data on exclusive $J/\psi$ production in ultraperipheral lead-lead collisions at $\sqrt{{s}_{NN}}=2.76$ and $\sqrt{{s}_{NN}}=5.02\phantom{\rule{0.28em}{0ex}}\mathrm{TeV}$. Especially at high-$\gamma A$ energies there is room for additional shadowing corrections, corresponding to triple-Pomeron terms or shadowing from large mass diffraction.

Published in: Physical Review C 99 (2019)