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This paper reports a measurement of the cross section for the pair production of top quarks in p{bar p} collisions at √s = 1.96 TeV at the Fermilab Tevatron. The data was collected from the CDF II detector in a set of runs with a total integrated luminosity of 1.1 fb−1. The cross section is measured in the dilepton channel, the subset of t{bar t} events in which both top quarks decay through t → Wb → l[nu]b, where l = e, [mu], or [tau]. The lepton pair is reconstructed as one identified electron or muon and one isolated track. The use of an isolated track to identify the second lepton increases the t{bar t} acceptance, particularly for the case in which one W decays as W → [tau][nu]. The purity of the sample may be further improved at the cost of a reduction in the number of signal events, by requiring an identified b-jet. They present the results of measurements performed with and without the request of an identified b-jet. the former is the first published CDF result for which a b-jet requirement is added to the dilepton selection. In the CDF data there are 129 pretag lepton + track candidate events, of which 69 are tagged. With the tagging information, the sample is divided into tagged and untagged sub-samples, and a combined cross section is calculated by maximizing a likelihood. The result is [sigma]{sub t{bar t}} = 9.6 ± 1.2(stat.){sub -0.5}{sup +0.6}(sys.) ± 0.6(lum.) pb, assuming a branching ratio of BR(W → l[nu]) = 10.8% and a top mass of m{sub t} = 175 GeV/c2.
We present the measurement of the t{bar t} cross section in the lepton plus jets channel with {ge} 1 and {ge} 2 secondary vertex tags. We use the scalar sum of transverse energies of the event (H{sub T}) to discriminate t{bar t} from the other backgrounds. We also use the transverse mass of the leptonic W-boson (M{sub T}{sup W}) to further reduce the Non-W backgrounds. We use a combination of data and Monte Carlo to estimate the backgrounds from electroweak processes, single top, fake leptons, W+ Light Flavor fake tags, and real W+ Heavy Flavor production. We obtain a value of {sigma} {sub {ge}1} = 8.7{sub -0.9}{sup +0.9}(stat){sub -0.9}{sup +1.2}(sys) pb for the {ge}1 tag cross section, and {sigma}{sub {ge}2} = 8.7{sub -1.6}{sup +1.8}(stat){sub -1.3}{sup +1.9}(sys) pb for the {ge}2 tag cross section. The authors also present a measurement of the t{bar t} cross section by fitting the N{sub jet} spectrum. They combine the =1 and {ge}2 tag cross sections to obtain {sigma}{sub t{bar t}} = 8.9{sub -0.9}{sup +0.9}(stat){sub -1.3}{sup +1.4}(syst)pb.
We present a measurement of the top quark pair (t{bar t}) production cross section ([sigma]{sub t{bar t}}) in p{bar p} collisions at √s = 1.96 TeV using 230 pb−1 of data collected by the D0 experiment at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), missing transverse energy, and jets in the final state. We employ lifetime-based b-jet identification techniques to further enhance the t{bar t} purity of the selected sample. For a top quark mass of 175 GeV, we measure [sigma]{sub t{bar t}} = 8.6{sub -1.5}{sup +1.6}(stat. + syst.) ± 0.6 (lumi.) pb, in agreement with the standard model expectation.
We present two measurements of the t{bar t} production cross section in collisions of protons and antiprotons at {radical}s = 196 TeV. We analyze a dataset of 310 {+-} 20 pb{sup -1} collected with the CDF 2 detector. In the first measurement, we select events with six to eight jets, at least one of which having a displaced secondary vertex, little or no missing transverse energy and optimized kinematical criteria consistent with the t{bar t} all-hadronic decay channel. In the second measurement, we select events with four or more jets, at least one of which having a displaced secondary vertex, high missing transverse energy, and optimized kinematical criteria consistent with the decay of t{bar t} to {tau}+jets. The averaged t{bar t} production cross section, determined from six different measurements using the CDF 2 detector in the dilepton, lepton+jets and all-hadronic decay channels, is also calculated to be {sigma}{sub t{bar t}} = 7.1 {+-} 0.6(stat) {+-} 0.7(syst) {+-} 0.4(lumi) pb, in agreement with the prediction of the standard model.
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.
Abstract Not Provided.
The authors present a measurement of the t{bar t} production cross section using events with one charged lepton and jets from p{bar p} collisions at a center-of-mass energy of 1.96 TeV. A b-tagging algorithm based on the probability of displaced tracks coming from the event interaction vertex is applied to identify b quarks from top decay. Using 318 pb−1 of data collected with the CDF II detector, they measure the t{bar t} production cross section in events with at least one restrictive (tight) b-tagged jet and obtain 8.9{sub -1.0}{sup +1.0}(stat.){sub -1.0}{sup +1.1}(syst.) pb. The cross section value assumes a top quark mass of m{sub t} is presented in the paper. This result is consistent with other CDF measurements of the t{bar t} cross section using different samples and analysis techniques, and has similar systematic uncertainties. They have also performed consistency checks by using the b-tagging probability function to vary the signal to background ratio and also using events that have at least two b-tagged jets.
This paper reports a measurement of the cross section for the pair production of top quarks in p{bar p} collisions at √s = 1.96 TeV at the Fermilab Tevatron. The data was collected from the CDF II detector in a set of runs with a total integrated luminosity of 1.1 fb−1. The cross section is measured in the dilepton channel, the subset of t{bar t} events in which both top quarks decay through t → Wb → l?b, where l = e,?, or?. The lepton pair is reconstructed as one identified electron or muon and one isolated track. The use of an isolated track to identify the second lepton increases the t{bar t} acceptance, particularly for the case in which one W decays as W →??. The purity of the sample may be further improved at the cost of a reduction in the number of signal events, by requiring an identified b-jet. They present the results of measurements performed with and without the request of an identified b-jet. the former is the first published CDF result for which a b-jet requirement is added to the dilepton selection. In the CDF data there are 129 pretag lepton + track candidate events, of which 69 are tagged. With the tagging information, the sample is divided into tagged and untagged sub-samples, and a combined cross section is calculated by maximizing a likelihood. The result is?{sub t{bar t}} = 9.6 ± 1.2(stat.){sub -0.5}{sup +0.6}(sys.) ± 0.6(lum.) pb, assuming a branching ratio of BR(W → l?) = 10.8% and a top mass of m{sub t} = 175 GeV/c2.
The direct observation of the top quark was first achieved at the Tevatron proton anti-proton collider at Fermilab. This discovery completed the third generation quark sector where the top quark is expected to accompany the bottom quark in the weak isospin doublet. This dissertation discusses the experimental verification of the production cross section as predicted by the Standard Model. A measurement of the t{bar t} production cross section using 107.9 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected with the Collider Detector at Fermilab between March of 2003 and June of 2003 is presented. The measurement focuses on the t{bar t} production in the ''lepton plus jets'' final state in which one of the W bosons from the t{bar t} decay subsequently decays leptonically to an electron or a muon, and the other decays hadronically. The B-tagging technique which utilizes the precision silicon detector tracking is used to enhance the signal for t{bar t} events relative to the background through identification of the bottom quark from its measurable lifetime. The t{bar t} production cross section is measured to be {sigma}{sub t{bar t}} = 4.5 {+-} 1.4(stat) {+-} 0.8(sys) pb.
The authors present a measurement of the top quark pair (t{bar t}) production cross section in p{bar p} collisions at √s = 1.96 TeV using events with two charged leptons in the final state. This analysis utilizes an integrated luminosity of 224-243 pb−1 collected with the D0 detector at the Fermilab Tevatron Collider. They observe 13 events in the e+e−, e? and ?+ ?− channels with an expected background of 3.2 ± 0.7 events. For a top quark mass of 175 GeV, we measure a t{bar t} production cross section of ?{sub t{bar t}} = 8.6{sub -2.7}{sup +3.2}(stat) ± 1.1(syst) ± 0.6(lumi) pb, consistent with the standard model prediction.