Understanding sequential quarkonium suppression with $\Upsilon(nS)$ measurements in pp and PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV with the CMS detector

The production cross sections of the $\Upsilon\textrm{(1S)}$, $\Upsilon\textrm{(2S)}$, and $\Upsilon\textrm{(3S)}$ states were measured separately using the CMS experimental apparatus, in proton-proton (pp) and lead-lead (PbPb) collisions at 5.02 TeV. The final results of the nuclear modification factors, $R_{AA}$, are reported of the three upsilon states as a function of transverse momentum ($p_{T}$), rapidity ($y$) and PbPb collision centrality. The data show a significant suppression of all three states following a sequential ordering, $R_{AA}(\Upsilon\textrm{(1S)}) > R_{AA}(\Upsilon\textrm{(2S)}) > R_{AA}(\Upsilon\textrm{(3S)})$. The suppression of $\Upsilon\textrm{(1S)}$ is larger than that seen at $\sqrt{s_{NN}}$ = 2.76 TeV, though the two are compatible within uncertainties. The $\Upsilon\textrm{(3S)}$ was not observed in PbPb collisions, being suppressed by more than a factor 10 at the 95$\%$ confidence level.