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| Total Pages | : 26 |
| Release | : 2007 |
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| Total Pages | : 4 |
| Release | : 2005 |
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We present two measurements of the t{bar t} production cross section in collisions of protons and antiprotons at √s = 196 TeV. We analyze a dataset of 310 ± 20 pb−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?+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?{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.
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| Total Pages | : 10 |
| Release | : 2009 |
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We present a measurement of the top quark pair production cross section in p{bar p} collisions at √s = 1.96 TeV using approximately 1 fb−1 of data collected with the D0 detector. We consider decay channels containing two high p{sub T} charged leptons where one lepton is identified as an electron or a muon while the other lepton can be an electron, a muon or a hadronically decaying [tau] lepton. For a mass of the top quark of 170 GeV, the measured cross section is 7.5{sub -1.0}{sup +1.0}(stat){sub -0.06}{sup +0.7}(syst){sub -0.5}{sup 0.6}(lumi) pb. Using l{sub {tau}} events only, they measure: [sigma]{sub t{bar t}} x B(t{bar t} → l{sub {tau}}b{bar b}) = 0.13{sub -0.08}{sup +0.09}(stat){sub -0.06}{sup 0.06}(syst)+{sub -0.02}{sup +0.02}(lumi) pb. Comparing the measured cross section as a function of the mass of the top quark with a partial next-to-next-to leading order Quantum Chromodynamics theoretical prediction, we extract a mass of the top quark of 171.5{sub -8.8}{sup +9.9} GeV, in agreement with direct measurements.
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| Total Pages | : 43 |
| Release | : 2009 |
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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?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.
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| Total Pages | : 9 |
| Release | : 2011 |
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We present a measurement of the t{bar t} production cross section [sigma]{sub t{bar t}} in p{bar p} collisions at √s = 1.96 TeV using 5.4 fb−1 of integrated luminosity collected with the D0 detector. We consider final states with at least two jets and two leptons (ee, e[mu], [mu][mu]), and events with one jet for the the e[mu] final state as well. The measured cross section is [sigma]{sub t{bar t}} = 7.36{sub -0.79}{sup +0.90} (stat + syst) pb. This result combined with the cross section measurement in the lepton + jets final state yields [sigma]{sub t{bar t}} = 7.56{sub -0.56}{sup +0.63}(stat + syst) pb, which agrees with the standard model expectation. The relative precision of 8% of this measurement is comparable to the latest theoretical calculations.
| Author | : Lucio Cerrito |
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| Total Pages | : 4 |
| Release | : 2005 |
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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.
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| Total Pages | : 43 |
| Release | : 2009 |
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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.
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| Total Pages | : 25 |
| Release | : 2006 |
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We report a new measurement of the t{bar t} production cross section in p{bar p} collisions at a center-of-mass energy of 1.96 TeV using events with one charged lepton (electron or muon), missing transverse energy, and jets. Using 425 pb−1 of data collected using the D0 detector at the Fermilab Tevatron Collider, and enhancing the t{bar t} content of the sample by tagging b jets with a secondary vertex tagging algorithm, the t{bar t} production cross section is measured to be: [sigma]{sub p{bar p} → t{bar t}+X} = 6.6 ± 0.9(stat + syst) ± 0.4(lum) pb. This cross section is the most precise D0 measurement to date for t{bar t} production and is in good agreement with standard model expectations.
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| Total Pages | : 45 |
| Release | : 2005 |
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The authors present a measurement of the top pair production cross section in p{bar p} collisions at √s = 1.96 TeV. We collect a data sample with an integrated luminosity of 194 ± 11 pb−1 with the CDF II detector at the Fermilab Tevatron. We use an artificial neural network technique to discriminate between top pair production and background processes in a sample of 519 lepton + jets events, which have one isolated energetic charged lepton, large missing transverse energy and at least three energetic jets. We measure the top pair production cross section to be [sigma]{sub t{bar t}} = 6.6 ± 1.1 ± 1.5 pb, where the first uncertainty is statistical and the second is systematic.
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| Release | : 2001 |
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The authors present the results of a new measurement of the t[anti t] production cross section using e[mu] channel in p[anti p] collisions at[radical]s= 1.8 TeV. This study corresponds to an integrated luminosity of 108.3[+-] 5.7 pb[sup[minus]1] acquired by the D0 detector during the Fermilab Tevatron Collider Run 1 (1992--1996). By using neural network techniques instead of the conventional analysis methods, the authors show that the signal acceptance can be increased by 10% (for m[sub t]= 172 GeV/c[sup 2]) while the background remains constant. Four e[mu] events are observed in data with an estimated background of 0.22[+-] 0.14 corresponding to a t[anti t] production cross section of 9.75[+-] 5.53 pb.
