Measurement of the tt-bar cross section in pp-bar collisions at sqrt[s]=1.96 TeV using dilepton events with a lepton plus track selection
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Aaltonen-2009-Measurement of the t.pdf
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Author(s) • • • • • • • • •
Xie, Si
Knuteson, Bruce O.
Henderson, C.
Hahn, Kristian Allan
Gomez-Ceballos, Guillelmo
Choudalakis, Georgios
Paus, Christoph M. E.
Goncharov, Maxim
Bauer, Gerry P
Makhoul, Khaldoun
Alternative Title
Measurement of the tt̅ cross section in pp̅ collisions at √s=1.96 TeV using dilepton events with a lepton plus track selection
Date Issued
June 2009
Journal
Physical Review D
Publisher
American Physical Society
Citation
CDF Collaboration et al. “Measurement of the tt-bar cross section in pp-bar collisions at s=1.96 TeV using dilepton events with a lepton plus track selection.” Physical Review D 79.11 (2009): 112007. © 2009 The American Physical Society
Version
Final published version
Abstract
This paper reports a measurement of the cross section for the pair production of top quarks in pp̅ collisions at √s=1.96 TeV at the Fermilab Tevatron. The data were collected from the CDF run II detector in a set of runs with a total integrated luminosity of 1.1 fb[superscript -1]. The cross section is measured in the dilepton channel, the subset of tt̅ events in which both top quarks decay through t→Wb→ℓνb, where ℓ=e, μ, or τ. 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 tt̅ acceptance, particularly for the case in which one W decays as W→τν. 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. We 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 subsamples, and a combined cross section is calculated by maximizing a likelihood. The result is σ[subscript tt̅] =9.6±1.2(stat)[subscript -0.5][superscript +0.6](sys)±0.6(lum) pb, assuming a branching ratio of BR(W→ℓν)=10.8% and a top mass of mt=175 GeV/c[superscript 2].
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
http://dx.doi.org/10.1103/PhysRevD.79.112007