%0 Journal Article %T Measurement of the t(t)over-barW and t(t)over-barZ production cross sections in pp collisions at root s=8 TeV with the ATLAS detector %A ATLAS Collaboration (Aad, G. et al %A Alvarez Piqueras, D. %A Cabrera Urban, S. %A Castillo Gimenez, V. %A Costa, M. J. %A Fernandez Martinez, P. %A Ferrer, A. %A Fiorini, L. %A Fuster, J. %A Garcia, C. %A Garcia Navarro, J. E. %A Gonzalez de la Hoz, S. %A Hernandez Jimenez, Y. %A Higon-Rodriguez, E. %A Irles Quiles, A. %A Jimenez Pena, J. %A Kaci, M. %A King, M. %A Lacasta, C. %A Lacuesta, V. R. %A Marti-Garcia, S. %A Mitsou, V. A. %A Pedraza Lopez, S. %A Perez Garcia-Estañ, M. T. %A Romero Adam, E. %A Ros, E. %A Salt, J. %A Sanchez Martinez, V. %A Soldevila, U. %A Sanchez, J. %A Valero, A. %A Valls Ferrer, J. A. %A Vos, M. %J Journal of High Energy Physics %D 2015 %V 11 %N 11 %I Springer %@ 1029-8479 %G English %F ATLASCollaborationAad_etal2015 %O WOS:000366139900001 %O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=2488), last updated on Fri, 01 Jan 2016 20:30:36 +0000 %X The production cross sections of top-quark pairs in association with massive vector bosons have been measured using data from pp collisions at root s = 8 TeV. The dataset corresponds to an integrated luminosity of 20.3 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 (t) over barW and t (t) over barZ processes simultaneously yields a significance of 5.0 sigma (4.2 sigma) over the background-only hypothesis for t (t) over barW (t (t) over barZ) production. The measured cross sections are sigma(t (t) over barW) = 369(-91)(+100) fb and sigma(t (t) over barZ) = 176(-52)(+58) fb. The background-only hypothesis with neither t (t) over barW nor t (t) over barZ production is excluded at 7.1 sigma. All measurements are consistent with next-to-leading-order calculations for the t (t) over barW and t (t) over barZ processes. %K Electroweak interaction %K Hadron-Hadron scattering %K Top physics %R 10.1007/JHEP11(2015)172 %U http://arxiv.org/abs/1509.05276 %U https://doi.org/10.1007/JHEP11(2015)172 %P 172-48pp