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

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Title:	Indications of Suppression of Excited Upsilon States in Pb-Pb Collisions at root(s)NN=2.76 TeV
Authors:	Chatrchyan,S;Khachatryan,V;Sirunyan,AM;Tumasyan,A;Adam,W;Bergauer,T;Dragicevic,M;Ero,J;Fabjan,C;Friedl,M;Fruhwirth,R;…etc.
Contributors:	電機工程學系
Keywords:	QUARK-GLUON PLASMA;HEAVY;DENSITY;QCD
Date:	2011
Issue Date:	2012-03-28 10:15:57 (UTC+8)
Publisher:	國立中央大學
Abstract:	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%.
Relation:	PHYSICAL REVIEW LETTERS
Appears in Collections:	[Department of Electrical Engineering] journal & Dissertation

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