Measurements of the cross sections for top quark pairs produced in association with a W or Z boson are presented, using 8 TeV pp 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 or the Z boson decays to two charged leptons. Signal events are identified by matching reconstructed objects in the detector to specific final state particles from tt⎯⎯W or tt⎯⎯Z decays. The tt⎯⎯W cross section is measured to be 382− 102+ 117 fb with a significance of 4.8 standard deviations from the background-only hypothesis. The tt⎯⎯Z cross section is measured to be 242− 55+ 65 fb with a significance of 6.4 standard deviations from the background-only hypothesis. These measurements are used to set bounds on five anomalous dimension-six operators that would affect the tt⎯⎯W and tt⎯⎯Z cross sections.
Observation of top quark pairs produced in association with a vector boson in pp collisions at sqrt(s) = 8 TeV
Sola, V.;AMAPANE, Nicola Carlo;ARGIRO', Stefano;BELLAN, Riccardo;COSTA, Marco;COVARELLI, Roberto;MIGLIORE, Ernesto;MONACO, Vincenzo;OBERTINO, Maria Margherita;ROMERO, Alessandra;SACCHI, Roberto;SOLANO, Ada Maria;
2016-01-01
Abstract
Measurements of the cross sections for top quark pairs produced in association with a W or Z boson are presented, using 8 TeV pp 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 or the Z boson decays to two charged leptons. Signal events are identified by matching reconstructed objects in the detector to specific final state particles from tt⎯⎯W or tt⎯⎯Z decays. The tt⎯⎯W cross section is measured to be 382− 102+ 117 fb with a significance of 4.8 standard deviations from the background-only hypothesis. The tt⎯⎯Z cross section is measured to be 242− 55+ 65 fb with a significance of 6.4 standard deviations from the background-only hypothesis. These measurements are used to set bounds on five anomalous dimension-six operators that would affect the tt⎯⎯W and tt⎯⎯Z cross sections.File | Dimensione | Formato | |
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