CMS-PAS-TOP-14-021

CMS-PAS-TOP-14-021
Measurement of top quark pair production in association with a W or Z boson using event reconstruction techniques
CMS Collaboration
July 2015

Abstract: A measurement of top quark pair production in association with a W or Z boson is presented, using 8 TeV proton-proton collision data corresponding to an integrated luminosity of 19.5 fb$^{-1}$, collected by the CMS experiment at the LHC. Final states are selected in which the associated W boson decays to a charged lepton and a neutrino ($\mathrm{W} \rightarrow \ell\nu$) or the Z boson decays to two charged leptons ($\mathrm{Z} \rightarrow \ell\ell$), where $\ell$ refers to an electron or muon. The $\mathrm{t \bar{t} W}$ cross section is measured to be $\sigma(\mathrm{t \bar{t} W}) = 382^{+117}_{-102}$ fb with a significance of 4.8 standard deviations from the background-only hypothesis. The $\mathrm{t \bar{t} Z}$ cross section is measured to be $\sigma(\mathrm{t \bar{t} Z}) = 242^{+65}_{-55}$ fb with a significance of 6.4 standard deviations from the background-only hypothesis. These measurements are used to find bounds for five anomalous dimension-six operators which would affect the $\mathrm{t \bar{t} W}$ and $\mathrm{t \bar{t} Z}$ cross sections.
Links: CDS record (PDF) ; inSPIRE record ; Public twiki page ; CADI line (restricted) ; These preliminary results are superseded in this paper, JHEP 01 (2016) 096. The superseded preliminary plots can be found here.

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