Observation of the $\Upsilon\textrm{(3S)}$ meson and sequential suppression of $\Upsilon$ states in PbPb collisions at $\sqrt{\mathrm{s_{NN}}}=5.02~\mathrm{TeV}$

The production of $\Upsilon\textrm{(2S)}$ and $\Upsilon\textrm{(3S)}$ mesons in lead-lead (PbPb) and proton-proton (pp) collisions is studied using the CMS detector at the LHC. Their nuclear modification factors, $R_{\textrm{AA}}$, derived from the ratio of yields measured in PbPb to pp collisions, are reported as functions of transverse momentum and PbPb collision centrality. The $\Upsilon\textrm{(3S)}$ meson is observed for the first time in PbPb collisions. The suppression is found to be stronger for $\Upsilon\textrm{(3S)}$ mesons compared to $\Upsilon\textrm{(2S)}$ mesons, extending the pattern of sequential suppression of bottomonium states in nuclear collisions previously seen for the $\Upsilon\textrm{(1S)}$ and $\Upsilon\textrm{(2S)}$ states. The results provide new constraints on models describing the dynamics of quarkonium states in heavy ion collisions.