Production of $\varUpsilon(\mathrm{nS})$ mesons in Pb+Pb and $\it{pp}$ collisions at 5.02 TeV with ATLAS

The measurement of the production of bottomonium states, $\mit{\Upsilon}(\text{1S})$, $\mit{\Upsilon}(\text{2S})$ and $\mit{\Upsilon}(\text{3S})$, in Pb+Pb and $pp$ collisions at a center-of-mass energy per nucleon pair of $5.02~\mathrm{TeV}$ is presented. The data correspond to integrated luminosities of $1.38~\mathrm{nb}^{-1}$ of Pb+Pb collisions collected in 2018 and $0.26~\mathrm{fb}^{-1}$ of $pp$ collisions collected in 2017 by the ATLAS detector. The measurements are performed in the dimuon decay channel in transverse momentum $p_\mathrm{T}^{\mu\mu} < 30~\mathrm{GeV}$, absolute rapidity $|y^{\mu\mu}|<1.5$, and the event centrality $0-80\%$. The production of three bottomonium states in Pb+Pb is compared to that in $pp$ collisions to extract the nuclear modification factor, $R_\mathrm{AA}$, as functions of event centrality, $p_\mathrm{T}^{\mu\mu}$ and $|y^{\mu\mu}|$. In addition, the relative suppression of the excited states $\mit{\Upsilon}(\text{nS})$ to the ground state $\mit{\Upsilon}(\text{1S})$ is studied. The measurements are compared to the previous CMS results and theoretical model predictions.