We present a precision measurement of the top-quark mass using the full sample of Tevatron √ s = 1.96 TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb −1 . Using a sample of tt candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the W boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with in situ calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, Mtop = 172.85 ± 0.71 (stat) ± 0.85 (syst) GeV/c 2 .PACS numbers: 14.65. Ha, 13.85.Ni, 13.85.Qk, 12.15.Ff The top quark (t) is by far the heaviest known elementary particle [1]. It contributes significantly to * Deceased † With visitors from

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We report the most sensitive direct search for pair production of fourth-generation bottom-like chiral quarks (b ′ ) each decaying promptly to tW . We search for an excess of events with an electron or muon, at least five jets (one indentified as due to a b or c quark) and an imbalance of transverse momentum using data from pp collisions collected by the CDF II detector at Fermilab with an integrated luminosity of 4.8 fb −1 . We observe events consistent with background expectation and calculate upper limits on the b ′ pair production cross section (σ b b′ 30 fb for m b ′ >375 GeV/c 2 ) and exclude m b ′ < 372 GeV/c 2 at 95% confidence level.

A search for new dielectron-mass resonances using data recorded by the CDF II detector and corresponding to an integrated luminosity of 5.7  fb(-1) is presented. No significant excess over the expected standard model prediction is observed. In this data set, an event with the highest dielectron mass ever observed (960  GeV/c(2)) was recorded. The results are interpreted in the Randall-Sundrum (RS) model. Combined with the 5.4  fb(-1) diphoton analysis, the RS-graviton lower-mass limit for the coupling k/M¯(Pl)=0.1 is 1058  GeV/c(2), making it the strongest limit to date.

The combination of searches performed by the CDF and D0 collaborations at the Fermilab Tevatron Collider for neutral Higgs bosons produced in association with b quarks is reported. The data, corresponding to 2.6 fb −1 of integrated luminosity at CDF and 5.2 fb −1 at D0, have been collected in final states containing three or more b jets. Upper limits are set on the cross section multiplied by the branching ratio varying between 44 pb and 0.7 pb in the Higgs boson mass range 90 to 300 GeV, assuming production of a narrow scalar boson. Significant enhancements to the production of Higgs bosons can be found in theories beyond the standard model, for example in supersymmetry. The results are interpreted as upper limits in the parameter space of the minimal supersymmetric standard model in a benchmark scenario favoring this decay mode.