Photoproduction of $J/\psi$ and $\psi(2S)$ in proton-proton ultraperipheral collisions at the LHC

Abstract

Using the framework of leading order perturbative QCD along with the CTEQ6L1 gluon distribution of the proton and high-energy HERA data on the $\gamma p \to J/\psi p$ and $\gamma p \to \psi(2S) p$ cross sections along with the corresponding H1 fit, we obtain a good description of the rapidity dependence of the cross sections of photoproduction of $J/\psi$ or $\psi(2S)$ mesons in proton--proton ultraperipheral collisions (UPCs) measured by the LHCb collaboration at the LHC. Within the same framework we also make predictions for the $pp \to pp J/\psi$ and $pp \to pp \psi(2S)$ UPC cross sections at $\sqrt{s_{NN}}=8$ and 14 TeV. We show that the possible contribution of the $p \to \Delta \gamma$ transition to the photon flux discernibly increases the $pp \to ppV$ UPC cross section and thus can affect the theoretical interpretation of results.