Measurement of Nuclear Modification Factors of $\Upsilon\textrm{(nS)}$ Mesons in $\text{PbPb}$ Collisions at $\sqrt{s_{_{\text{NN}}}} = 5.02~\mathrm{TeV}$

The cross sections of $\Upsilon\textrm{(1S)}$, $\Upsilon\textrm{(2S)}$, and $\Upsilon\textrm{(3S)}$ production in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02~\mathrm{TeV}$ are reported. The nuclear modification factors, $R_\mathrm{AA}$, derived from the PbPb-to-pp ratio of yields for each state, are studied as a function of rapidity, transverse momentum and centrality. A strong modification is observed for all $\Upsilon$ states. The suppression of $\Upsilon\textrm{(1S)}$ seen in $\text{PbPb}$ collisions at $\sqrt{s_{\mathrm{NN}}}$ = $5.02~\mathrm{TeV}$ is stronger than the previous one measured at $\sqrt{s_{\mathrm{NN}}} = 2.76~\mathrm{TeV}$, consistent with an increase in the medium temperature at the higher energy. We obtain an upper limit on the production of $\Upsilon\textrm{(3S)}$ of $0.071$ at $95\%$ confidence level, the smallest value measured for a hadron $R_\mathrm{AA}$ in heavy ion collisions so far.