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|a Xie, Si
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|a Massachusetts Institute of Technology. Department of Physics
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|a Massachusetts Institute of Technology. Laboratory for Nuclear Science
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|a Paus, Christoph M. E.
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|a Xie, Si
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|a Makhoul, K.
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|a Knuteson, Bruce O.
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|a Henderson, C.
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|a Hahn, Kristian Allan
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|a Goncharov, M.
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|a Gomez-Ceballos, Guillelmo
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|a Choudalakis, Georgios
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|a Bauer, Gerry P.
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|a Paus, Christoph M. E.
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|a Makhoul, K.
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|a Knuteson, Bruce O.
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|a Henderson, C.
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|a Hahn, Kristian Allan
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|a Goncharov, M.
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|a Gomez-Ceballos, Guillelmo
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|a Choudalakis, Georgios
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|a Bauer, Gerry P.
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|a Paus, Christoph M. E.
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|a Search for the neutral current top quark decay t-->Zc using the ratio of Z-boson+4 jets to W-boson+4 jets production
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|a Search for the neutral current top quark decay t→Zc using the ratio of Z-boson+4 jets to W-boson+4 jets production
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|b American Physical Society,
|c 2010-02-26T19:35:40Z.
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|z Get fulltext
|u http://hdl.handle.net/1721.1/51837
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|a We have used the Collider Detector at Fermilab (CDF-II) to search for the flavor-changing neutral-current (FCNC) top-quark decay t→Zc using a technique employing ratios of W and Z production, measured in pp̅ data corresponding to an integrated luminosity of 1.52 fb[superscript -1]. The analysis uses a comparison of two decay chains, pp̅ →tt̅ →WbWb→ℓνbjjb and pp̅ →tt̅ →ZcWb→ℓℓcjjb, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the modeling of acceptance and efficiency for lepton identification over the multiyear data set using another ratio of W and Z production, in this case the observed ratio of inclusive production of W to Z bosons. To improve the discrimination against standard model backgrounds to top-quark decays, we calculate the top-quark mass for each event with two leptons and four jets assuming it is a tt̅ event with one of the top quarks decaying to Zc. For additional background discrimination we require at least one jet to be identified as originating from a b quark. No significant signal is found and we set an upper limit on the FCNC branching ratio Br(t→Zc) using a likelihood constructed from the ℓℓcjjb top-quark mass distribution and the number of ℓνbjjb events. Limits are set as a function of the helicity of the Z boson produced in the FCNC decay. For 100% longitudinally-polarized Z bosons we find limits of 8.3% and 9.3% (95% C.L.) depending on the assumptions regarding the theoretical top-quark pair production cross section.
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|a Academy of Finland
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|a Slovak R&D Agency
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|a Programa Consolider-Ingenio 2010, Spain
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|a Ministerio de Ciencia e Innovación, Spain
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|a Russian Foundation for Basic Research
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|a Institut National de Physique Nucleaire et Physique des Particules/CNRS
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|a Royal Society, United Kingdom
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|a Science and Technology Facilities Council, United Kingdom
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|a Korean Research Foundation
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|a Korean Science and Engineering Foundation
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|a Bundesministerium für Bildung und Forschung, Germany
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|a Alfred P. Sloan Foundation
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|a Swiss National Science Foundation
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|a National Science Council of the Republic of China
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|a Natural Sciences and Engineering Research Council of Canada
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|a Ministry of Education, Culture, Sports, Science and Technology of Japan
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|a Italian Istituto Nazionale di Fisica Nucleare
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|a National Science Foundation
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|a United States Department of Energy
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|a en_US
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|a Article
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|t Physical Review D
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