Observation of single top quark production and measurement of |Vtb| with CDF

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Aaltonen , T , Mehtälä , P , Orava , R , Saarikko , H , Österberg , K & CDF Collaboration 2010 , ' Observation of single top quark production and measurement of |Vtb| with CDF ' Physical Review D : Particles, Fields, Gravitation and Cosmology , vol 82 , no. 11 , pp. 112005 . , 10.1103/PhysRevD.82.112005

Title: Observation of single top quark production and measurement of |Vtb| with CDF
Author: Aaltonen, Timo; Mehtälä, Petteri; Orava, Risto; Saarikko, Heimo; Österberg, Kenneth; CDF Collaboration
Contributor: University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
University of Helsinki, Department of Physics
Belongs to series: Physical Review D : Particles, Fields, Gravitation and Cosmology
ISSN: 1550-7998
Abstract: We report the observation of electroweak single top quark production in 3.2 fb-1 of ppbar collision data collected by the Collider Detector at Fermilab at sqrt{s}=1.96 TeV. Candidate events in the W+jets topology with a leptonically decaying W boson are classified as signal-like by four parallel analyses based on likelihood functions, matrix elements, neural networks, and boosted decision trees. These results are combined using a super discriminant analysis based on genetically evolved neural networks in order to improve the sensitivity. This combined result is further combined with that of a search for a single top quark signal in an orthogonal sample of events with missing transverse energy plus jets and no charged lepton. We observe a signal consistent with the standard model prediction but inconsistent with the background-only model by 5.0 standard deviations, with a median expected sensitivity in excess of 5.9 standard deviations. We measure a production cross section of 2.3+0.6-0.5(stat+sys) pb, extract the CKM matrix element value |Vtb|=0.91+0.11-0.11 (stat+sys)+-0.07(theory), and set a lower limit |Vtb|>0.71 at the 95% confidence level, assuming m_t=175 GeVc^2.
Peer review status: Peer reviewed
URI: http://hdl.handle.net/10138/24162
Date: 2010-12-15
Subject: 114 Physical sciences
hep-ex


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