Indications of Suppression of Excited Υ States in Pb-Pb Collisions at sNN=2.76 TeV Academic Article uri icon


  • A comparison of the relative yields of Υ resonances in the μ(+)μ(-) 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 Υ(2S) and Υ(3S) excited states to the Υ(1S) ground state in Pb-Pb and pp collisions, [Υ(2S+3S)/Υ(1S)](Pb-Pb)/[Υ(2S+3S)/Υ(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%.

altmetric score

  • 1.75

author list (cited authors)

  • Chatrchyan, S., Khachatryan, V., Sirunyan, A. M., Tumasyan, A., Adam, W., Bergauer, T., ... Weinberg, M.

citation count

  • 145

publication date

  • July 2011