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Register a new userEvidence for $s$-channel Single-Top-Quark Production in Events with one Charged Lepton and two Jets at CDF
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We report evidence for $s$-channel single-top-quark production in proton-antiproton collisions at center-of-mass energy $sqrt{s}= 1.96 mathrm{TeV}$ using a data set that corresponds to an integrated luminosity of $9.4 mathrm{fb}^{-1}$ collected by the Collider Detector at Fermilab. We select events consistent with the $s$-channel process including two jets and one leptonically decaying $W$ boson. The observed significance is $3.8$ standard deviations with respect to the background-only prediction. Assuming a top-quark mass of $172.5 mathrm{GeV}/c^2$, we measure the $s$-channel cross section to be $1.41^{+0.44}_{-0.42} mathrm{pb}$.
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We report a measurement of single top quark production in proton-antiproton collisions at a center-of-mass energy of sqrt{s} = 1.96 TeV using a data set corresponding to 7.5 fb-1 of integrated luminosity collected by the Collider Detector at Fermilab. We select events consistent with the single top quark decay process t to Wb to l{ u}b by requiring the presence of an electron or muon, a large imbalance of transverse momentum indicating the presence of a neutrino, and two or three jets including at least one originating from a bottom quark. An artificial neural network is used to discriminate the signal from backgrounds. We measure a single top quark production cross section of 3.04+0.57-0.53 pb and set a lower limit on the magnitude of the coupling between the top quark and bottom quark |Vtb| > 0.78 at the 95% credibility level.
The first search for single top quark production from the exchange of an $s$-channel virtual $W$ boson using events with an imbalance in the total transverse momentum, $b$-tagged jets, and no identified leptons is presented. The full data set collected by the Collider Detector at Fermilab, corresponding to an integrated luminosity of 9.45 fb$^{-1}$ from Fermilab Tevatron proton-antiproton collisions at a center of mass energy of 1.96 TeV, is used. Assuming the electroweak production of top quarks of mass 172.5 GeV/$c^2$ in the $s$-channel, a cross section of $1.12_{-0.57}^{+0.61}$ (stat+syst) pb, with a significance of 1.9 standard deviations, is measured. This measurement is combined with a previous result obtained from events with an imbalance in total transverse momentum, $b$-tagged jets, and exactly one identified lepton, yielding a cross section of $1.36_{-0.32}^{+0.37}$ (stat+syst) pb, with a significance of 4.2 standard deviations.
We present a measurement of the mass of the top quark from ppbar collisions at 1.96 TeV observed with the Collider Detector at Fermilab (CDF) at the Fermilab Tevatron Run II. The events have the decay signature of ppbar to ttbar in the lepton plus jets channel in which at least one jet is identified as coming from a secondary vertex and therefore a b-hadron. The largest systematic uncertainty, the jet energy scale (JES), is convoluted with the statistical error using an in-situ measurement of the hadronic W boson mass. We calculate a likelihood for each event using leading-order ttbar and W+jets cross-sections and parameterized parton showering. The final measured top quark mass and JES systematic is extracted from a joint likelihood of the product of individual event likelihoods. From 118 events observed in 680 pb-1 of data, we measure a top quark mass of 174.09 +- 2.54 (stat+JES) +- 1.35 (syst) GeV/c2.
We report a measurement of the mass of the top quark in lepton+jets final states of ppbar->ttbar data corresponding to 2.6 fb^{-1} of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Using a matrix element method, we combine an insitu jet energy calibration with our standard jet energy scale derived in studies of {gamma}+jet and dijet events and employ a novel flavor-dependent jet response correction to measure a top-quark mass of mt = 176.01 +/- 1.64 GeV. Combining this result with our previous result obtained on an independent data set, we measure a top-quark mass of mt = 174.94 +/- 1.49 GeV for a total integrated luminosity of 3.6 fb^{-1}.
We present an analysis of top-antitop quark production and decay into a tau lepton, tau neutrino, and bottom quark using data from $9 {rm fb}^{-1}$ of integrated luminosity at the Collider Detector at Fermilab. Dilepton events, where one lepton is an energetic electron or muon and the other a hadronically-decaying tau lepton, originating from proton-antiproton collisions at $sqrt{s} = 1.96 TeV$ are used. A top-antitop quark production cross section of $8.1 pm 2.1 {rm pb}$ is measured, assuming standard-model top-quark decays. By separately identifying for the first time the single-tau and the ditau components, we measure the branching fraction of the top quark into tau lepton, tau neutrino, and bottom quark to be $(9.6 pm 2.8) %$. The branching fraction of top-quark decays into a charged Higgs boson and a bottom quark, which would imply violation of lepton universality, is limited to be less than $5.9%$ at $95%$ confidence level.
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