2023

Eskola, K. J.; Guzey, V.; Löytäinen, T.; Paukkunen, H.; Flett, C. A.

We make predictions for the cross section of coherent J/ψ photoproduction in Pb–Pb and O–O ultraperipheral collisions (UPCs) at the LHC as a function of the J/ψ rapidity y in the framework of collinear factorization and next-to-leading order (NLO) perturbative QCD. We quantify the strong scale dependence and significant uncertainties due to nuclear PDFs and show that our approach provides a reasonable description of the LHC data on coherent J/ψ photoproduction in Pb–Pb UPCs. We demonstrate that these uncertainties are reduced by approximately a factor of 10 in the scaled ratio of the O–O and Pb–Pb UPC cross sections. Our analysis indicates the dominance of the quark contribution to the UPC cross section at central rapidities, which affects the interpretation of the UPC data.