# Measurement of the $t\bar{t}W$ and $t\bar{t}Z$ production cross sections in $pp$ collisions at $\sqrt{s} = 8 \mathrm{\ Te\kern -0.1em V}$ with the ATLAS detector

Abstract : The production cross sections of top-quark pairs in association with massive vector bosons have been measured using data from $pp$ collisions at $\sqrt{s} = 8 \mathrm{\ Te\kern -0.1em V}$. The dataset corresponds to an integrated luminosity of $20.3\ \mathrm{fb}^{-1}$ collected by the ATLAS detector in 2012 at the LHC. Final states with two, three or four leptons are considered. A fit to the data considering the $t\bar{t}W$ and $t\bar{t}Z$ processes simultaneously yields a significance of $5.0\sigma$ ($4.2\sigma$) over the background-only hypothesis for $t\bar{t}W$ ($t\bar{t}Z$) production. The measured cross sections are $\sigma_{t\bar{t}W} = 369^{+100}_{-91}$ fb and $\sigma_{t\bar{t}Z} = 176^{+58}_{-52}$ fb. The background-only hypothesis with neither $t\bar{t}W$ nor $t\bar{t}Z$ production is excluded at $7.1\sigma$. All measurements are consistent with next-to-leading-order calculations for the $t\bar{t}W$ and $t\bar{t}Z$ processes.
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Journal articles
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http://hal.in2p3.fr/in2p3-01201768
Contributor : Emmanuelle Vernay <>
Submitted on : Friday, September 18, 2015 - 8:20:25 AM
Last modification on : Tuesday, November 5, 2019 - 4:32:43 PM

### Citation

G. Aad, S. Albrand, J. Collot, S. Crépé-Renaudin, P.A. Delsart, et al.. Measurement of the $t\bar{t}W$ and $t\bar{t}Z$ production cross sections in $pp$ collisions at $\sqrt{s} = 8 \mathrm{\ Te\kern -0.1em V}$ with the ATLAS detector. Journal of High Energy Physics, Springer Verlag (Germany), 2015, 11, pp.172. ⟨10.1007/JHEP11(2015)172⟩. ⟨in2p3-01201768⟩

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