Download or read book Measurement of t bar t Helicity Fractions and Spin Correlation in p bar p Collisions at sqrt s written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of t bar t Spin Correlations and Top quark Polarization Using Dilepton Final States in Pp Collisions at sqrt s written by and published by . This book was released on 2013 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the t bar t Production Cross Section in p bar P Collisions at sqrt s written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we report a measurement of the t{anti t} production cross section in p{anti p} collisions at √{ovr s} = 1.96 TeV using data corresponding to an integrated luminosity of 2.2 fb−1 collected with the CDF II detector at the Tevatron accelerator. We select events with significant missing transverse energy and high jet multiplicity. This measurement vetoes the presence of explicitly identified electrons and muons, thus enhancing the tau contribution of t{anti t} decays. Signal events are discriminated from the background using a neural network and heavy flavor jets are identified by a secondary-vertex tagging algorithm. We measure a t{anti t} production cross section of 7.99 ± 0.55 (stat) ± 0.76 (syst) ± 0.46 (lumi) pb, assuming a top mass m{sub top} = 172.5 GeV/c2, in agreement with previous measurements and standard model predictions.
Download or read book Spin Correlations in Tt Events from Pp Collisions written by Boris Lemmer and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis introduces readers to the Standard Model, the top quark and its properties, before explaining the concept of spin correlation measurement. The first measurement of top quark spin correlations at the LHC in the lepton+jets decay channel is presented. As the heaviest elementary particle, the top quark plays an essential role in the Standard Model of elementary particle physics. In the case of top quarks being produced in pairs at hadron colliders, the Standard Model predicts their spins to be correlated. The degree of correlation depends on both the production mechanism and properties of the top quark. Any deviation from the Standard Model prediction can be an indicator for new physics phenomena. The thesis employs an advanced top quark reconstruction algorithm including dedicated identification of the up- and down-type quarks from the W boson decay.
Download or read book Top Physics written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the t{bar t} production cross section using 194 pb−1 of CDF II data using events with a high transverse momentum electron or muon, three or more jets, and missing transverse energy. The measurement assumes 100% t --> Wb branching fraction. Events consistent with t{bar t} decay are found by identifying jets containing heavy flavor semileptonic decays to muons. The dominant backgrounds are evaluated directly from the data. Based on 20 candidate events and an expected background of 9.5 " 1.1 events, we measure a production cross section of 5.3 " 3.3{sub -1.0}{sup +1.3} pb, in agreement with the standard model.
Download or read book Measurement of the Inclusive t bar t Production Cross Section in p bar p Collisions at sqrt s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The inclusive cross section of top quark-antiquark pairs produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is measured in the lepton+jets and dilepton decay channels. The data sample corresponds to 9.7 fb-1 of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of [sigma]$t\bar{t}$=7.26±0.13(stat)$+0.57\atop{-0.50}$(syst) pb which is consistent with standard model predictions. We also perform a likelihood fit to the measured and predicted top quark mass dependence of the inclusive cross section, which yields a measurement of the pole mass of the top quark. The extracted value is mt=172.8±1.1(theo)$+3.3\atop{-3.1}$(exp) GeV.
Download or read book Measurement of the ttbar Production Cross Section in 2 Fb 1 of ppbar Collisions at sqrt s written by and published by . This book was released on 2009 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the t{bar t} production cross section in p{bar p} collisions at (square root)s = 1.96 TeV using events containing a high transverse momentum electron or muon, three or more jets, and missing transverse energy. Events consistent with t{bar t} decay are found by identifying jets containing candidate heavy-flavor semileptonic decays to muons. The measurement uses a CDF Run II data sample corresponding to 2 fb−1 of integrated luminosity. Based on 248 candidate events with three or more jets and an expected background of 79.5 ± 5.3 events, we measure a production cross section of 9.1 ± 1.6 pb.
Download or read book Measurement of the Ratio B t to Wb B t to Wq in Pp Collisions at sqrt s written by and published by . This book was released on 2014 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ratio of the top-quark branching fractions R=B(t to Wb)/B(t to Wq), where the denominator includes the sum over all down-type quarks (q = b, s, d), is measured in the t t-bar dilepton final state with proton-proton collision data at sqrt(s)=8 TeV from an integrated luminosity of 19.7 inverse femtobarns, collected with the CMS detector. In order to quantify the purity of the signal sample, the cross section is measured by fitting the observed jet multiplicity, thereby constraining the signal and background contributions. By counting the number of b jets per event, an unconstrained value of R=1.014 +/- 0.003 (stat.) +/- 0.032 (syst.) is measured, in good agreement with the standard model prediction. A lower limit R> 0.955 at the 95% confidence level is obtained after requiring R ;=1, and a lower limit on the Cabibbo-Kobayashi-Maskawa matrix element abs(V[tb]) 0.975 is set at 95% confidence level. The result is combined with a previous CMS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, Gamma[t]=1.36 +/- 0.02 (stat.) +0.14/-0.11 (syst.) GeV.
Download or read book Measuring Transversity in Polarized P p Collisions with Di hadron Correlations at s written by Keith Landry and published by . This book was released on 2016 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transversity distribution, $h_1(x)$, of a transversely polarized proton describes the probability of partons with polarization parallel to the parent proton, carrying a momentum fraction $x$ of the parent proton. This distribution is fundamental for our understanding of the proton spin structure but still very much unknown for values of $x$ larger than about 0.15. We study transversely spin-polarized proton collisions at $\sqrt{s}=200$ GeV from STAR, because polarized p+p collisions at RHIC can access this $x$ region and, with a higher scale and transverse momentum, probe a different kinematic regime than SIDIS. We find sizable spin asymmetries in di-hadron correlations, which can be used to directly probe the transversity distribution of quarks inside protons because they arise from a transversely spin polarized quark fragmenting into two hadrons by the Interference Fragmentation Function.
Download or read book Measurement of the Ttbar Production Cross Section in Ppbar Collisions at Sqrt s written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the top quark pair production cross section in p{bar p} collisions at √s = 1.96 TeV using a data sample corresponding to 1.7 fb−1 of integrated luminosity collected with the Collider Detector at Fermilab. We reconstruct t{bar t} events in the lepton+jets channel, consisting of e[nu]+jets and [mu][nu]+jets final states. The dominant background is the production of W bosons in association with multiple jets. To suppress this background, we identify electrons from the semileptonic decay of heavy-flavor jets ('soft electron tags'). From a sample of 2196 candidate events, we obtain 120 tagged events with a background expectation of 51 ± 3 events, corresponding to a cross section of [sigma]{sub t{bar t}} = 7.8 ± 2.4 (stat) ± 1.6 (syst) ± 0.5 (lumi) pb. We assume a top-quark mass of 175 GeV/c2. This is the first measurement of the t{bar t} cross section with soft electron tags in Run II of the Tevatron.
Download or read book A Measurement of the T Anti t Production Cross Section in P Anti p Collisions at S 1 2 written by and published by . This book was released on 2008 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: I present a measurement of the t{bar t} production cross section at √s = 1.96 TeV using 2034 pb−1 of CDF Run II data using events with a high transverse momentum electron or muon, three or more jets, and missing transverse energy. The measurement assumes a t → Wb branching fraction of 100 percent. Events consistent with t{bar t} decay are found by identifying jets containing heavy-flavor semileptonic decays to muons. The dominant backgrounds are evaluated directly from the data. Based on 248 candidate events and an expected background of 86.8 ± 5.6 events, I measure a production cross section of 8.7 ± 1.1{sub -0.8}{sup +0.9} ± 0.6 pb, in agreement with the Standard Model.
Download or read book Modern Drawings and Watercolours written by and published by . This book was released on 1967 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Ttbar Production Cross Section in Ppbar Collisions at S written by and published by . This book was released on 2005 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the measurement of the top quark pair production cross section in p{bar p} collisions at √s = 1.96 TeV using 318 pb−1 of data collected by the CDF detector at the Fermilab Tevatron. We measure the cross section in events with one high transverse momentum electron or muon, large missing transverse energy and three or more jets, where at least one bottom quarks from the top quark decay is identified via a secondary vertex tagging algorithm. The measured t{bar t} cross section is 8.7{sub -0.9}{sup +0.9}(stat){sub -0.9}{sup +1.2}(syst) pb, assuming a top quark mass of 178 GeV. The cross section measurement in the subsample in which both b-quark jets are identified gives 10.1{sub -1.4}{sup +1.6}(stat){sub -1.4}{sup +2.1}(syst) pb. We present one additional measurement of the t{bar t} cross section in the same dataset but without the b-tagging requirement. Top quark events are distinguished from the primary background of W boson production with associated jets using an artificial neural network method with a variety of kinematic quantities. This measurement uses a larger dataset albeit with a smaller t{bar t} fraction. The t{bar t} cross section without b-tagging is measured to be 6.0 ± 0.8(stat) ± 1.0(syst) pb.
Download or read book Measurement of the t bar t Production Cross Section in Pp Collisions at sqrt s written by and published by . This book was released on 2014 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top-quark pair production cross section is measured in final states with one electron or muon and one hadronically decaying [tau] lepton from the process $t\bar{t}$ to (l[nu]l) ([tau][nu][tau]) $b\bar{b}$, where l = e, [mu]. The data sample corresponds to an integrated luminosity of 19.6 fb-1 collected with the CMS detector in proton-proton collisions at $\sqrt{s}$ =8 TeV. The measured cross section [sigma]$t\bar{t}$ = 257 ± 3 (stat) ± 24 (syst) ± 7 (lumi) pb, assuming a top-quark mass of 172.5 GeV, is consistent with the standard model prediction.
Download or read book Measurement of the Top Pair Production Cross Section in the Dilepton Decay Channel in Ppbar Collisions at Sqrt S written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the t{bar t} production cross section in p{bar p} collisions at √s = 1.96 TeV using events with two leptons, missing transverse energy, and jets is reported. The data were collected with the CDF II Detector. The result in a data sample corresponding to an integrated luminosity 2.8 fb−1 is: [sigma]{sub t{bar t}} = 6.27 ± 0.739(stat) ± 0.63(syst) ± 0.39(lum) pb for an assumed top mass of 175 GeV/c2.
Download or read book Measurement of the Ttbar Production Cross Section in Ppbar Collisions at S 1 2 written by and published by . This book was released on 2005 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the measurement of the top quark pair production cross section in p{bar p} collisions at √s = 1.96 TeV using 318 pb−1 of data collected by the CDF detector at the Fermilab Tevatron. We measure the cross section in events with one high transverse momentum electron or muon, large missing transverse energy and three or more jets, where at least one bottom quarks from the top quark decay is identified via a secondary vertex tagging algorithm. The measured t{bar t} cross section is 8.7{sub -0.9}{sup +0.9}(stat){sub -0.9}{sup +1.2}(syst) pb, assuming a top quark mass of 178 GeV. The cross section measurement in the subsample in which both b-quark jets are identified gives 10.1{sub -1.4}{sup +1.6}(stat){sub -1.4}{sup +2.1}(syst) pb. We present one additional measurement of the t{bar t} cross section in the same dataset but without the b-tagging requirement. Top quark events are distinguished from the primary background of W boson production with associated jets using an artificial neural network method with a variety of kinematic quantities. This measurement uses a larger dataset albeit with a smaller t{bar t} fraction. The t{bar t} cross section without b-tagging is measured to be 6.0 ± 0.8(stat) ± 1.0(syst) pb.
Download or read book Evidence for T bar T Production at the Tevatron written by and published by . This book was released on 1994 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We summarize here the results of the ''counting experiments'' by the CDF Collaboration in the search of t{bar t} production in p{bar p} collisions at (square root)s = 1800 TeV at the Tevatron. We analyze their statistical significance by calculating the probability that the observed excess is a fluctuation of the expected backgrounds, and assuming the excess is from top events, extract a measurement of the t{bar t} production cross-section.
