We report the observation of electroweak single top quark production in 3.2fb⊃-1 of pp̄ collision data collected by the Collider Detector at Fermilab at √s=1.96TeV. 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 2.3-0.5+0.6(stat+sys)pb, extract the value of the Cabibbo-Kobayashi-Maskawa matrix element |Vtb|=0.91-0.11+0. 11(stat+sys)±0.07(theory), and set a lower limit |Vtb|>0.71 at the 95%C.L., assuming mt=175GeV/c2.
Publication Source (Journal or Book title)
Physical Review D - Particles, Fields, Gravitation and Cosmology
Aaltonen, T., Adelman, J., Álvarez González, B., Amerio, S., Amidei, D., Anastassov, A., Annovi, A., Antos, J., Apollinari, G., Appel, J., Apresyan, A., Arisawa, T., Artikov, A., Asaadi, J., Ashmanskas, W., Attal, A., Aurisano, A., Azfar, F., Badgett, W., Barbaro-Galtieri, A., Barnes, V., Barnett, B., Barria, P., Bartos, P., Bauer, G., Beauchemin, P., Bedeschi, F., & Beecher, D. (2010). Observation of single top quark production and measurement of |V tb| with CDF. Physical Review D - Particles, Fields, Gravitation and Cosmology, 82 (11) https://doi.org/10.1103/PhysRevD.82.112005