Direct Top-Quark Width Measurement at CDF

• Main Authors: Bauer, Gerry P. (Contributor), Gomez-Ceballos, Guillelmo (Contributor), Goncharov, Maxim (Contributor), Makhoul, Khaldoun (Contributor), Paus, Christoph M. E. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2011-04-28T20:33:39Z.
• Subjects: Article
• Online Access: Get fulltext

 We present a measurement of the top-quark width in the lepton+jets decay channel of tt̅ events produced in pp̅ collisions at Fermilab's Tevatron collider and collected by the CDF II detector. From a data sample corresponding to 4.3  fb-1 [fb superscript -1] of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of the hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different top-quark widths (Γt) [gamma subscript t] and deviations from nominal jet energy scale (ΔJES)[delta subscript JES] to perform a simultaneous fit for both parameters, where ΔJES [delta subscript JES] is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of Γt<7.6  GeV [gamma subscript t<7.6 GeV] and a two-sided 68% CL interval of 0.3  GeV<Γt<4.4  GeV [GeV<gamma subscript t<4.4 GeV]] for a top-quark mass of 172.5  GeV/c2 [GeV / c superscript 2], which are consistent with the standard model prediction.