We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of γ+jet+missing transverse energy events in pp collisions at s√=1.96  TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570  pb−1 of collision data, we observe 2 events, consistent with the background estimate of 1.3±0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with χ˜01→γG˜ and place the world-best 95% C.L. lower limit on the χ˜01 mass of 101  GeV/c2 at τχ˜01=5  ns

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).

We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1 fb;-1 of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7+/-0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to 6 standard deviations. The measured cross section is sigma(pp-->WZ)=5.0(-1.6)(+1.8) pb, consistent with the standard model expectation.

We report on measurements of the inclusive jet production cross section as a function of the jet transverse momentum in p p collisions at s p 1:96 TeV, using the k T algorithm and a data sample corresponding to 1:0 fb ÿ1 collected with the Collider Detector at Fermilab in run II. The measurements are carried out in five different jet rapidity regions with jy jet j < 2:1 and transverse momentum in the range

We report a measurement of the top-quark mass, Mt, in the dilepton decay channel of tt→bℓ'+νℓ′b¯ℓ−ν¯ℓ using an integrated luminosity of 1.0  fb−1 of pp collisions collected with the CDF II detector. We apply a method that convolutes a leading-order matrix element with detector resolution functions to form event-by-event likelihoods; we have enhanced the leading-order description to describe the effects of initial-state radiation. The joint likelihood is the product of the likelihoods from 78 candidate events in this sample, which yields a measurement of Mt=164.5±3.9(stat.)±3.9(syst.)  GeV/c2, the most precise measurement of Mt in the dilepton channel