Observation of Sequential Suppression in PbPb Collisions
The suppression of the individual $$\Upsilon(nS)$$ 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 μb–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 $$\Upsilon(nS)$$ yields are measured from the dimuon invariant mass spectra. The suppression of the $$\Upsilon(nS)$$ yields in PbPb relative to the yields in pp, scaled by the number of nucleon-nucleon collisions, RAA, is measured as a function of the collision centrality. Integrated over centrality, the RAA 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 $$\Upsilon(1S)$$, $$\Upsilon(2S)$$, and $$\Upsilon(3S)$$ states, respectively. The results demonstrate the sequential suppression of the $$\Upsilon(nS)$$ states in PbPb collisions at LHC energies.
- Research Organization:
- Univ. of Kansas, Lawrence, KS (United States). Center for Research
- Sponsoring Organization:
- USDOE
- Contributing Organization:
- CMS Collaboration
- Grant/Contract Number:
- FG02-96ER40981
- OSTI ID:
- 1075208
- Alternate ID(s):
- OSTI ID: 2325014
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Vol. 109 Journal Issue: 22; ISSN 0031-9007
- Publisher:
- American Physical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Measurement of meson production in pp and PbPb collisions at TeV
Study of Z production in PbPb and pp collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV in the dimuon and dielectron decay channels