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-0.1
em 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 …

The production cross sections of top-quark pairs in association with massive vector bosons
have been measured using pp collision data corresponding to an integrated luminosity of
20.3/fb, collected by the ATLAS detector in 2012 at the LHC. Final states with two, three or
four leptons are considered. The fit to the data considering both signal processes
simultaneously yields significances of 5.0 σ and 4.2 σ over the background-only hypothesis
for the ttW and ttZ processes, respectively. The measured cross-sections are σttW= 369+ …