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

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F12%3A10290257" target="_blank" >RIV/00216208:11320/12:10290257 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1007/JHEP12(2012)034" target="_blank" >http://dx.doi.org/10.1007/JHEP12(2012)034</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1007/JHEP12(2012)034" target="_blank" >10.1007/JHEP12(2012)034</a>

Result language
angličtina
Original language name
Observation of Z decays to four leptons with the CMS detector at the LHC
Original language description
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
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BF - Elementary particle theory and high energy physics
OECD FORD branch
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Project
<a href="/en/project/LA08015" target="_blank" >LA08015: Collaboration of the Czech Republic with CERN</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year
2012
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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