| Seminar Date: | Friday, September 21, 2012 |
| Time: | 11:00 AM - 12:30 PM |
| Location: | KIPAC Auditorium |
| Abstract: | The top quark, the heaviest elementary particle known, provides an interesting probe of the Standard Model (SM). Deviations from the decay and production predictions from the SM give a model-independent test for physics beyond the SM. I present a search for flavor changing neutral current (FCNC) processes in top-quark decays by the ATLAS Collaboration. Data collected from pp collisions at the LHC with a center-of-mass energy of 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 SM dominant mode t->Wb. 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. |
| Speaker: | Arely Cortes Gonzalez - University of Illinois
 Dr. Arely Cortes-Gonzalez earned her BS in physics in 2006 from the Universita Tecnologico de Monterrey, Mexico, and her Ph.D. in 2012 from the University of Illinois, Urbana-Champaign. A member of the ATLAS collaboration, she worked on the offline muon track monitoring, and the measurement of the t-tbar cross section in the dileptonic channel, introducing a "track-lepton" selection which contributed to an increased signal efficiency. She applied this to her thesis analysis, which she will describe in this talk.
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