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 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 tt¯W and tt¯Z processes simultaneously yields a significance of 5.0σ (4.2σ) over the background-only hypothesis for tt¯W (tt¯Z) production. The measured cross sections are σtt¯W=369+100−91 fb and σtt¯Z=176+58−52 fb. The background-only hypothesis with neither tt¯W nor tt¯Z production is excluded at 7.1σ. All measurements are consistent with next-to-leading-order calculations for the tt¯W and tt¯Z processes.

Measurement of the ttbarW and ttbarZ production cross sections in pp collisions at sqrt(s) = 8 TeV with the ATLAS detector

CHIODINI, GABRIELE;GORINI, Edoardo;PRIMAVERA, Margherita;SPAGNOLO, Stefania Antonia;VENTURA, Andrea;
2015-01-01

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 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 tt¯W and tt¯Z processes simultaneously yields a significance of 5.0σ (4.2σ) over the background-only hypothesis for tt¯W (tt¯Z) production. The measured cross sections are σtt¯W=369+100−91 fb and σtt¯Z=176+58−52 fb. The background-only hypothesis with neither tt¯W nor tt¯Z production is excluded at 7.1σ. All measurements are consistent with next-to-leading-order calculations for the tt¯W and tt¯Z processes.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11587/395580
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