Coherent photoproduction of vector mesons in heavy ion ultraperipheral collisions: Update for run 2 at the CERN Large Hadron Collider

TL;DR

This paper predicts cross sections for coherent vector meson photoproduction in Pb-Pb ultraperipheral collisions at 5.02 TeV, highlighting the roles of photon fluctuations and nuclear shadowing, and extends previous models to run 2 LHC conditions.

Contribution

It provides updated theoretical predictions for vector meson photoproduction cross sections at LHC run 2 energies, incorporating photon fluctuations and nuclear shadowing effects.

Findings

Photon fluctuations significantly affect light meson production.

Nuclear gluon shadowing dominates quarkonium photoproduction.

Forward neutron emission enhances photon energy range.

Abstract

We make predictions for the cross sections of coherent photoproduction of $\rho$, $\phi$, $J/\psi$, $\psi(2S)$, and $\Upsilon(1S)$ mesons in Pb-Pb ultraperipheral collisions (UPCs) at $\sqrt{s_{NN}}=5.02$ TeV in the kinematics of run 2 at the Large Hadron Collider extending the approaches successfully describing the available Pb-Pb UPC data at $\sqrt{s_{NN}}=2.76$ TeV. Our results illustrate the important roles of hadronic fluctuations of the photon and inelastic nuclear shadowing in photoproduction of light vector mesons on nuclei and the large leading twist nuclear gluon shadowing in photoproduction of quarkonia on nuclei. We show that the ratio of $\psi(2S)$ and $J/\psi$ photoproduction cross sections in Pb-Pb UPCs is largely determined by the ratio of these cross sections on the proton. We also argue that UPCs with electromagnetic excitations of the colliding ions followed by the forward neutron emission allows one to significantly increase the range of photon energies accessed in vector meson photoproduction on nuclei.