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Abstract:

We present a search for new physics in events with two high pT leptons of the same electric charge, using data with an integrated luminosity of 6.1fb-1. The observed data are consistent with standard model predictions. We set 95% C.L. lower limits on the mass of doubly charged scalars decaying to like-sign dileptons, mH±±>190-245GeV/ c2, assuming 100% BR to ee, μμ or eμ. © 2011 American Physical Society.

Abstract:

A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy √s=1.96TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of tt̄ pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parametrized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction (ΔJES) amounts to an additional in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2fb-1 of integrated luminosity, the top-quark mass is measured to be mt=172.4±1.4(stat+ΔJES)±1. 3(syst)GeV/c2. © 2011 American Physical Society.

Abstract:

This paper reports a search for nonstandard model topquark resonances, Z′, decaying to tt̄→W+bW -b̄, where both W decay to quarks. We examine the top-antitop quark invariant mass spectrum for the presence of narrow resonant states. The search uses a data sample of pp̄ collisions at a center of mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of 2.8fb-1. No evidence for top-antitop quark resonant production is found. We place upper limits on the production cross section times branching ratio for a specific topcolor assisted technicolor model in which the Z′ has a width of Γ Z′=0.012MZ′. Within this model, we exclude a Z′ boson with masses below 805GeV/c2 at the 95% confidence level. © 2011 American Physical Society.

Abstract:

We present a study of Bs0 decays to the CP-odd final state J/ψf 0(980) with J/ψ→μ+μ- and f 0(980)→π+π-. Using pp̄ collision data with an integrated luminosity of 3.8fb-1 collected by the CDF II detector at the Tevatron we measure a Bs0 lifetime of τ(Bs0→J/ψf0(980))=1.70-0.11+0.12(stat)±0.03(syst) ps. This is the first measurement of the Bs0 lifetime in a decay to a CP eigenstate and corresponds in the standard model to the lifetime of the heavy Bs0 eigenstate. We also measure the product of branching fractions of Bs0→J/ψf0(980) and f0(980)→π +π- relative to the product of branching fractions of Bs0→J/ψ and →K+K- to be Rf0 /=0.257±0.020(stat)±0.014(syst), which is the most precise determination of this quantity to date. © 2011 American Physical Society.

Abstract:

We report on a search for the production of the Higgs boson decaying to two bottom quarks accompanied by two additional quarks. The data sample used corresponds to an integrated luminosity of approximately 4fb-1 of pp̄ collisions at √s=1.96TeV recorded by the CDF II experiment. This search includes twice the integrated luminosity of the previous published result, uses analysis techniques to distinguish jets originating from light flavor quarks and those from gluon radiation, and adds sensitivity to a Higgs boson produced by vector boson fusion. We find no evidence of the Higgs boson and place limits on the Higgs boson production cross section for Higgs boson masses between 100GeV/c2 and 150GeV/c2 at the 95% confidence level. For a Higgs boson mass of 120GeV/c2, the observed (expected) limit is 10.5 (20.0) times the predicted standard model cross section. © 2011 American Physical Society.