We report a measurement of the single top quark production cross section in 2.2 fb −1 of pp collision data collected by the Collider Detector at Fermilab at √ s = 1.96 TeV. Candidate events are classified as signal-like by three parallel analyses which use likelihood, matrix element, and neural network discriminants. These results are combined in order to improve the sensitivity. We observe a signal consistent with the standard model prediction, but inconsistent with the backgroundonly model by 3.7 standard deviations with a median expected sensitivity of 4.9 standard deviations. We measure a cross section of 2.2 +0.7 −0.6 (stat + sys) pb, extract the CKM matrix element value |V tb | = 0.88 +0.13 −0.12 (stat + sys) ± 0.07(theory), and set the limit |V tb | > 0.66 at the 95% C.L.

We report the first observation of single top quark production using 3.2 fb −1 of pp collision data with √ s = 1.96 TeV collected by the Collider Detector at Fermilab. The significance of the observed data is 5.0 standard deviations, and the expected sensitivity for standard model production and decay is in excess of 5.9 standard deviations. Assuming mt = 175 GeV/c 2 , we measure a cross section of 2.3 +0.6 −0.5 (stat + syst) pb, extract the CKM matrix element value |V tb | = 0.91 ± 0.11(stat + syst) ± 0.07(theory), and set the limit |V tb | > 0.71 at the 95% C.L.

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We present a search for new particles which produce narrow two-jet (dijet) resonances using protonantiproton collision data corresponding to an integrated luminosity of 1:13 fb À1 collected with the CDF II detector. The measured dijet mass spectrum is found to be consistent with next-to-leading-order perturbative QCD predictions, and no significant evidence of new particles is found. We set upper limits at the 95% confidence level on cross sections times the branching fraction for the production of new particles decaying into dijets with both jets having a rapidity magnitude jyj < 1. These limits are used to determine the mass exclusions for the excited quark, axigluon, flavor-universal coloron, E 6 diquark, coloroctet techni-, W 0 , and Z 0 .

We present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. We analyze events from the single lepton plus jets final state (tt-->W(+)bW(-)b-->lnubqq'b). The top-quark mass is extracted using a direct calculation of the probability density that each event corresponds to the tt final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb(-1) of integrated luminosity, we achieve the single most precise measurement of the top-quark mass, 170.8+/-2.2(stat.)+/-1.4(syst.) GeV/c(2).