A comparison of the relative yields of Upsilon resonances in the mu(+)mu(-) 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 GeV/c and pseudorapidity below 2.4, the double ratio of the Upsilon(2S) and Upsilon(3S) excited states to the Upsilon(1S) ground state in Pb-Pb and pp collisions, [Upsilon(2S + 3S)/Upsilon(1S)](Pb-Pb) /[Upsilon 2S + 3S)/Upsilon(1S)](pp), is found to be 0.31(-0.15)(+0.19) (stat_ +/- 0.03(syst). The probability to obtain the measured value, or lower, if the true double ratio is unity, is calculated to be less than 1%.

Indications of Suppression of Excited Upsilon States in Pb-Pb Collisions at root(s)NN=2.76 TeV

GALANTI, MARIO;BELLAN, PAOLO;BISELLO, DARIO;BRANCA, ANTONIO;CARLIN, ROBERTO;GASPARINI, FABRIZIO;GASPARINI, UGO;GOZZELINO, ANDREA;MARGONI, MARTINO;MENEGUZZO, ANNA TERESA;NESPOLO, MASSIMO;PERROZZI, LUCA;POZZOBON, NICOLA;RONCHESE, PAOLO;SIMONETTO, FRANCO;TOSI, MIA;VANINI, SARA;ZOTTO, PIERLUIGI;ZUMERLE, GIANNI;M. Grassi;ROSSIN, ROBERTO;A. Gaz;