Indications of Suppression of Excited Υ States in Pb-Pb Collisions at sNN=2.76 TeV

A comparison of the relative yields of $\ensuremath{\Upsilon}$ resonances in the ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decay channel in Pb-Pb and $pp$ collisions at a center-of-mass energy per nucleon pair of 2.76 TeV is performed with data collected with the CMS detector at the LHC. Using muons of transverse momentum above $4\text{ }\text{ }\mathrm{GeV}/c$ and pseudorapidity below 2.4, the double ratio of the $\ensuremath{\Upsilon}(2S)$ and $\ensuremath{\Upsilon}(3S)$ excited states to the $\ensuremath{\Upsilon}(1S)$ ground state in Pb-Pb and $pp$ collisions, $[\ensuremath{\Upsilon}(2S+3S)/\ensuremath{\Upsilon}(1S){]}_{\mathrm{Pb}\mathrm{\text{\ensuremath{-}}}\mathrm{Pb}}/[\ensuremath{\Upsilon}(2S+3S)/\ensuremath{\Upsilon}(1S){]}_{pp}$, is found to be ${0.31}_{\ensuremath{-}0.15}^{+0.19}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{syst})$. The probability to obtain the measured value, or lower, if the true double ratio is unity, is calculated to be less than 1%.