Strong suppression of $\varUpsilon$ excited states in PbPb collisions at $\sqrt{s_{NN}} = 5.02~\mathrm{TeV}$

Measurements of $\varUpsilon$ mesons, produced in pp and PbPb collisions at $\sqrt{s_{NN}} = 5.02~\mathrm{TeV}$ and reconstructed via their dimuon decay channel, are reported using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states to the ground state in both PbPb and pp collisions at the same energy. The $\varUpsilon$(2S) double ratio is studied as a function of centrality, dimuon transverse momentum, and rapidity. We find suppression in all centrality bins and no variation with kinematics. For the $\varUpsilon$(3S), no significant signal is found in the PbPb data. A search in centrality bins shows that the double ratio is significantly below unity at all centralities, an observation that indicates strong suppression in heavy-ion collisions. The centrality-integrated double ratios are $0.308 \pm 0.055 \mathrm{(stat)} \pm 0.017 \mathrm{(syst)}$ for the $\varUpsilon$(2S) and less than $0.26$ at $95\%$ confidence level for the $\varUpsilon$(3S).