Observation of Z decays to four leptons with the CMS detector at the LHC
Name
Chatrchyan2012_Article_ObservationOfZDecaysToFourLept.pdf
Description
Published version
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800.88 KB
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Unknown
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Author(s)
The CMS Collaboration
Apyan, Aram
Bauer, Gerry P
Bendavid, Joshua L.
Busza, Wit
Butz, Erik M.
Cali, Ivan Amos
Chan, M.
Dutta, Valentina
Gomez-Ceballos, Guillelmo
Date Issued
2012
Journal
Journal of High Energy Physics
Publisher
Springer Science and Business Media LLC
Citation
Chatrchyan, S., et al. "Observation of Z Decays to Four Leptons with the Cms Detector at the Lhc." Journal of High Energy Physics 12 (2012): 28.
Version
Final published version
Abstract
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 s=7 TeV collected by the CMS detector at the Large Hadron Collider. A pronounced resonance peak, with a statistical significance of 9.7 σ, 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 → 4ℓ)=({4.2-0.8+0.9 (stat.)±0.2(syst.))×times 10-6 and agrees with the standard model prediction of 4.45 × 10-6. The measured cross section times branching fraction is σ (pp → Z)B(Z →4ℓ)=112-20+23(stat.)-5+7 (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.[Figure not available: see fulltext.] © 2012 CERN for the benefit of the CMS collaboration.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
Terms of Use
Creative Commons Attribution 4.0 International license
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1007/JHEP12(2012)034
