Exclusive J/Ψ Production and Gluon GPDs Effects

Study of exclusive photoproduction of $${J \\mathord{\\left/ {\\vphantom {J \\psi }} \\right. \\kern-0em} \\psi }$$ mesons was carried out in a factorization approach. Generalized parton distributions (GPDs) for gluons, which play an important role here, are constructed using the double distribution representation. The obtained cross sections of $${J \\mathord{\\left/ {\\vphantom {J \\psi }} \\right. \\kern-0em} \\psi }$$ production in a wide energy range are in good agreement with the experiment. The spin asymmetries in the $${J \\mathord{\\left/ {\\vphantom {J \\psi }} \\right. \\kern-0em} \\psi }$$ production were estimated. These calculations were extended to the of $${J \\mathord{\\left/ {\\vphantom {J \\psi }} \\right. \\kern-0em} \\psi }$$ mesons production in ultraperipherical $$pp$$ collisions. It was shown a good agreement of our results with the LHCb data. Predictions have been made for the NICA energy range. The model results can be used to study the gluon GPDs in future colliders.