Indications of suppression of excited $$\Upsilon$$ states in PbPb collisions at $$\sqrt{S_{NN}}$$ = 2.76 TeV

Journal Article · Fri Jul 01 00:00:00 EDT 2011 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.107.052302· OSTI ID:1176946

Chatrchyan, S. ^[1]; et al.,

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1. Yerevan Physics Institute (Armenia)

A comparison of the relative yields of Upsilon resonances in the mu(+) mu(-) decay channel in PbPb and pp collisions at a centre-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 PbPb and pp collisions,(Upsilon(2S+3S)/Upsilon(1S)[PbPb])/(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, has been calculated to be less than 1%.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Contributing Organization: CMS Collaboration
• OSTI ID: 1176946
• Report Number(s): CERN-PH-EP-2011-074; CMS-HIN-11-007; FERMILAB-PUB-11-735-CMS; arXiv_eprint>arXiv eprint number arXiv:1105.4894
• Journal Information: Physical Review Letters, Vol. 107, Issue 5
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS