Observation of Z decays to four leptons with the CMS detector at the LHC

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	Observation of Z decays to four leptons with the CMS detector at the LHC
	CMS Collaboration
刊名	JOURNAL OF HIGH ENERGY PHYSICS
	2012
期号	12
关键词	PARTICLE PAIR SEARCH BOSON ORDER
通讯作者	Chatrchyan, S (reprint author), Yerevan Phys Inst, Yerevan 375036, Armenia.
英文摘要	The first observation of the Z boson decaying to four leptons in proton-proton collisions is presented. The analyzed data set corresponds to an integrated luminosity of 5.02 fb(-1) at root s = 7 TeV collected by the CMS detector at the Large Hadron Collider. A pronounced resonance peak, with a statistical significance of 9.7 sigma, is observed in the distribution of the invariant mass of four leptons (electrons and/or muons) with mass and width consistent with expectations for Z boson decays. The branching fraction and cross section reported here are defined by phase space restrictions on the leptons, namely, 80 < m(4l) < 100 GeV, where m(4l) is the invariant mass of the four leptons, and m(ll) > 4 GeV for all pairs of leptons, where m(ll) is the two-lepton invariant mass. The measured branching fraction is B(Z -> 4(l)) = 4.2(-0.8)(+0.9)(stat.) +/- 0.2(syst.)) x 10(-6) and agrees with the standard model prediction of 4.45 x 10(-6). The measured cross section times branching fraction is sigma(pp -> Z) B (Z -> 4l) = 112(-20)(+23)(stat.) +/-(+7)(-5)(syst.)(-2)(+3) (lumi.) fb, also consistent with the standard model prediction of 120 fb. The four-lepton mass peak arising from Z -> 4l decays provides a calibration channel for the Higgs boson search in the H -> ZZ -> 4l decay mode.
学科主题	Physics
类目[WOS]	Physics, Particles & Fields
收录类别	SCI
语种	英语
WOS记录号	WOS:000313123800034
公开日期	2016-02-25
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/213422]
专题	高能物理研究所_粒子天体物理中心
作者单位	中国科学院高能物理研究所
推荐引用方式 GB/T 7714	CMS Collaboration. Observation of Z decays to four leptons with the CMS detector at the LHC[J]. JOURNAL OF HIGH ENERGY PHYSICS,2012(12).
APA	CMS Collaboration.(2012).Observation of Z decays to four leptons with the CMS detector at the LHC.JOURNAL OF HIGH ENERGY PHYSICS(12).
MLA	CMS Collaboration."Observation of Z decays to four leptons with the CMS detector at the LHC".JOURNAL OF HIGH ENERGY PHYSICS .12(2012).