Observation of Sequential upsilon Suppression in PbPb Collisions


Chatrchyan S., Khachatryan V., Sirunyan A. M., Tumasyan A., Adam W., Aguilo E., ...Daha Fazla

PHYSICAL REVIEW LETTERS, cilt.109, sa.22, 2012 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 109 Sayı: 22
  • Basım Tarihi: 2012
  • Doi Numarası: 10.1103/physrevlett.109.222301
  • Dergi Adı: PHYSICAL REVIEW LETTERS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

The suppression of the individual gamma (nS) states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150 mu b(-1) and 230 nb(-1), respectively, collected in 2011 by the CMS experiment at the LHC, at a center-of-mass energy per nucleon pair of 2.76 TeV. The gamma (nS) yields are measured from the dimuon invariant mass spectra. The suppression of the gamma (nS) yields in PbPb relative to the yields in pp, scaled by the number of nucleon-nucleon collisions, R-AA, is measured as a function of the collision centrality. Integrated over centrality, the R-AA values are 0.56 +/- 0.08(stat) +/- 0.07(syst), 0.12 +/- 0.04(stat) +/- 0.02(syst), and lower than 0.10 (at 95% confidence level), for the gamma (1S), gamma (2S), and gamma (3S) states, respectively. The results demonstrate the sequential suppression of the gamma (nS) states in PbPb collisions at LHC energies.