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


Chatrchyan, S.; ...; Godinović, Nikola; Lelas, Damir; Pleština, Roko; Polić, Dunja; Puljak, Ivica; Antunović, Željko; Kovač, Marko; Brigljević, Vuko et al.
Observation of Z decays to four leptons with the CMS detector at the LHC // Journal of High Energy Physics, 1212 (2012), 034-1 doi:10.1007/JHEP12(2012)034 (međunarodna recenzija, članak, znanstveni)


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

Autori
Chatrchyan, S. ; ... ; Godinović, Nikola ; Lelas, Damir ; Pleština, Roko ; Polić, Dunja ; Puljak, Ivica ; Antunović, Željko ; Kovač, Marko ; Brigljević, Vuko ; Đurić, Senka ; Kadija, Krešo ; Luetić, Jelena ; Morović, Srećko ; ... ; Mekterović, Darko ; ... ; Swanson, J.

Izvornik
Journal of High Energy Physics (1029-8479) 1212 (2012); 034-1

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Hadron-Hadron Scattering

Sažetak
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 inverse femtobarns at sqrt(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 to 4l) = (4.2 /+0.9/-0.8 (stat.) +/- 0.2 (syst.)) 10E-6 and agrees with the standard model prediction of 4.45 10E-6. The measured cross section times branching fraction is sigma(pp to Z) B(Z to 4 l) = 112 +23/-20 (stat.) +7/-5 (syst.) +3/-2 (lumi.) fb, also consistent with the standard model prediction of 120 fb. The four-lepton mass peak arising from Z to 4 l decays provides a calibration channel for the Higgs boson search in the H to ZZ to 4 l decay mode.

Izvorni jezik
Engleski

Znanstvena područja
Fizika



POVEZANOST RADA


Projekt / tema
023-0982887-3064 - Potraga za Higgsovim bozonom i novom fizikom detektorom CMS (Ivica Puljak, )
098-0982887-2878 - Eksperimentalna fizika na LHC energijama (Krešo Kadija, )

Ustanove
Fakultet elektrotehnike, strojarstva i brodogradnje, Split,
Institut "Ruđer Bošković", Zagreb

Časopis indeksira:


  • Current Contents Connect (CCC)
  • Web of Science Core Collection (WoSCC)
    • Science Citation Index Expanded (SCI-EXP)
    • SCI-EXP, SSCI i/ili A&HCI
  • Scopus


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