Abstract
High energy ultra-peripheral collisions provide unique circumstances to examine the exclusive photoproduction of heavy mesons. The Pb+Pb collisions generated at CERN's Large Hadron Collider at √sNN = 5:02 TeV provide new data which has been predicted to have a reconstructable signal for the ηc meson. Analysis of ALICE's Run 2 Pb+Pb collision data for evidence of ηc production was performed using nine decay channels of the ηc. STARlight and PYTHIA8 Monte Carlo simulations were used to understand the detector acceptance for each channel.
A total luminosity of 101.7 µb^-1 was analyzed for this study. All of the ηc decay channels containing only charged pions and kaons in the final state were analyzed. After background subtraction, a total of 28.3 ± 13.0 ± 7.5 ηc candidates, and 25.3 ± 6.8 ± 0.81 J/ψ candidates were observed. The first uncertainty is statistical and the second uncertainty is systematic. The upper limit for the photoproduction cross section ratio of ηc to J/ψ is σηc=σJ/ψ < 0:268 ± 0:147 ± 0:073.