A search for flavor-changing neutral currents in top-quark decays t -> Zq is performed in events produced from the decay chain (tt) over bar -> 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 19.7 fb(-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.

Search for Flavor-Changing Neutral Currents in Top-Quark Decays t → Zq in pp Collisions at √s=8 TeV

CIOCCI, MARIA AGNESE;MESSINEO, ALBERTO MARIA;RIZZI, ANDREA;TONELLI, GUIDO EMILIO;Bianchini, L.;Marini, A. C.;
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 (tt) over bar -> 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 19.7 fb(-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
Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Eroe, J.; Fabjan, C.; Friedl, M.; Fruehwirth, ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/765654
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