Energy dependence of exclusive $J/\psi$ photoproduction off protons in ultra-peripheral p-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV

TL;DR

This study measures how the cross section of exclusive $J/mbda$ photoproduction off protons varies with energy in ultra-peripheral p-Pb collisions at 5.02 TeV, providing data that aligns with theoretical models and previous experiments.

Contribution

First measurement of the energy dependence of exclusive $J/mbda$ photoproduction in ultra-peripheral p-Pb collisions at LHC energies, extending previous HERA and LHC results.

Findings

Cross section follows a power law dependence on energy.

Results are consistent with previous measurements and theoretical models.

Data covers a wide energy range from 40 to 550 GeV.

Abstract

The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of $J/\psi$ vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV. The e$^+$e$^-$ and $\mu^+\mu^-$ decay channels are used to measure the cross section as a function of the rapidity of the $J/\psi$ in the range $-2.5 < y < 2.7$, corresponding to an energy in the $\gamma$p centre-of-mass in the interval $40 < W_{\gamma\mathrm{p}}<550$ GeV. The measurements, which are consistent with a power law dependence of the exclusive $J/\psi$ photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.