Measurement of the $\psi(2S)$ to $J/\psi$ cross-section ratio as a function of centrality in PbPb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV

TL;DR

This paper measures the ratio of $(2S)$ to $J/$ production in lead-lead collisions at 5.02 TeV, finding no centrality dependence, which informs understanding of quarkonium suppression in quark-gluon plasma.

Contribution

It provides the first detailed measurement of the $(2S)$ to $J/$ cross-section ratio as a function of centrality in PbPb collisions at this energy, comparing results with theoretical models.

Findings

Ratio shows no dependence on collision centrality

Results agree with some theoretical predictions

Provides new data for quarkonium suppression studies

Abstract

The dissociation of quarkonium states with different binding energies produced in heavy-ion collisions is a powerful probe for investigating the formation and properties of the quark-gluon plasma. The ratio of production cross-sections of $\psi(2S)$ and $J/\psi$ mesons times the ratio of their branching fractions into the dimuon final state is measured as a function of centrality using data collected by the LHCb detector in PbPb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV. The measured ratio shows no dependence on the collision centrality, and is compared to the latest theory predictions and to the recent measurements in literature.