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A search for flavor changing neutral currents in  top-quark decays in pp collision data collected with the ATLAS detector at √s=7 TeV

Dra. Arely Cortés González
Universidad de Illinois, Urbana-Champaign



Este seminario se llevará a cabo en la

Sala de Conferencias 111B/302
Facultad de Ciencias Físico Matemáticas – BUAP

Jueves 16 de agosto de 2012
12:00 hrs.



Resumen:

A search for flavor changing neutral current (FCNC) processes in top-quark decays by the ATLAS Collaboration is presented. Data collected from pp collisions at the LHC with a center-of-mass energy of sqrt(s)=7 TeV during 2011, corresponding to an integrated luminosity of 2.1 fb^{-1} were used. A search was performed for top-quark pair-production events, with one top quark decaying through the t --> Zq FCNC (q=u,c) channel and the other through the Standard Model dominant mode t --> Wq. Only decays of the Z-boson to charged leptons and leptonic W-boson decays were considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons, at least two jets and missing transverse momentum from the undetected neutrino.

No evidence for an FCNC signal was found. An upper limit on the t --> Zq branching ratio of BR(t --> Zq ) < 0.73% is set at the 95% confidence level.