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Register a new userMeasurement of the Top Pair Production Cross Section in the Lepton + Jets Channel Using a Jet Flavor Discriminant
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We present a new method to measure the top quark pair production cross section and the background rates with 2.7 fb$^{-1}$ of data from $pbar{p}$ collisions at $sqrt{s} =1.96$ TeV collected with the CDF II Detector. The size of the dataset was chosen to directly show the improvements of this new method. We select events with a single electron or muon, missing transverse energy, and at least one b-tagged jet. We perform a simultaneous fit to a jet flavor discriminant across nine samples defined by the number of jets and b-tags. We measure a top cross section of $sigma_{tbar{t}} = 7.64 pm 0.57 mathrm{(stat + syst)} pm 0.45 mathrm{(luminosity)}$ pb. An advantage of this approach is that many systematic uncertainties are measured in situ and inversely scale with integrated luminosity.
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The top quark, discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton antiproton collider at Fermilab, has undergone intense studies in the last 20 years. Currently, CDF and D0 converge on their measurements of top-antitop quark production cross sections using the full Tevatron data sample. In these proceedings, the latest results on inclusive and differential measurements of top-antitop quark production cross sections at the Tevatron are reported.
We present a measurement of the total {it WW} and {it WZ} production cross sections in $pbar{p}$ collision at $sqrt{s}=1.96$ TeV, in a final state consistent with leptonic $W$ boson decay and jets originating from heavy-flavor quarks from either a $W$ or a $Z$ boson decay. This analysis uses the full data set collected with the CDF II detector during Run II of the Tevatron collider, corresponding to an integrated luminosity of 9.4 fb$^{-1}$. An analysis of the dijet mass spectrum provides $3.7sigma$ evidence of the summed production processes of either {it WW} or {it WZ} bosons with a measured total cross section of $sigma_{WW+WZ} = 13.7pm 3.9$~pb. Independent measurements of the {it WW} and {it WZ} production cross sections are allowed by the different heavy-flavor decay-patterns of the $W$ and $Z$ bosons and by the analysis of secondary-decay vertices reconstructed within heavy-flavor jets. The productions of {it WW} and of {it WZ} dibosons are independently seen with significances of $2.9sigma$ and $2.1sigma$, respectively, with total cross sections of $sigma_{WW}= 9.4pm 4.2$~pb and $sigma_{WZ}=3.7^{+2.5}_{-2.2}$~pb. The measurements are consistent with standard-model predictions.
We present results for the total top-pair production cross section at the Tevatron and the LHC. Our predictions supplement fixed-order results with resummation of soft logarithms and Coulomb singularities to next-to-next-to-leading (NNLL) logarithmic accuracy and include top-antitop bound-state effects. The effects of resummation, the dependence on the PDF set used, the residual sources of theoretical uncertainty and their implication for measurements of the top-quark mass are discussed.
A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy $sqrt{s}=1.96$ TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of $tbar t$ 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 parameterized 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 ($JES$) amounts to an additional textit{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 3.2 $fb^{-1}$ of integrated luminosity, the top-quark mass is measured to be $m_t = rm 172.4 pm 1.4:(stat+JES) pm 1.3:(syst) GeV/{it c}^2$.
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.
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