A search for flavor-changing neutral currents in top-quark decays t→Zq is performed in events produced from the decay chain tt̄→Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A data set collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7fb-1 of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus, no evidence for flavor-changing neutral currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t→Zq branching fraction greater than 0.05% at the 95% confidence level. © 2014 CERN, for the CMS Collaboration.

Search for flavor-changing neutral currents in top-quark decays t →zq in pp collisions at s =8TeV

ALBERGO, Sebastiano Francesco;CAPPELLO, GIGI;CHIORBOLI, MASSIMILIANO;COSTA, Salvatore;GIORDANO, FERDINANDO;POTENZA, Renato Carlo;TRICOMI, Alessia Rita;TUVE', Cristina Natalina;
2014-01-01

Abstract

A search for flavor-changing neutral currents in top-quark decays t→Zq is performed in events produced from the decay chain tt̄→Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A data set collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7fb-1 of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus, no evidence for flavor-changing neutral currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t→Zq branching fraction greater than 0.05% at the 95% confidence level. © 2014 CERN, for the CMS Collaboration.
2014
Nuclear Physics; Thermodynamics; Models, Theoretical; Neutrons; Physics and Astronomy (all)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/310427
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