Measurement of the single top quark cross section in the lepton plus jets final state in proton-antiproton collisions at a center of mass energy of 1.96 TeV using the CDF II detector.

We present a measurement of the single top quark cross section in the lepton plus jets final state using an integrated luminosity corresponding to 7.5/fb of collision data collected by the Collider Detector at Fermilab. The single top candidate events are identified by the signature of a charged lepton, large missing transverse energy, and two or three jets with at least one of them identified as originating from a bottom quark. A new Monte Carlo generator powheg is used to model the single top quark production processes, which include s-channel, t-channel, and Wt-channel. A neural network multivariate method is exploited to discriminate the single top quark signal from the comparatively large backgrounds. We measure a single top production cross section of 3.04+0.57−0.53 (stat. + syst.) pb assuming mtop = 172.5 GeV/c^2. In addition, we extract the CKM matrix element value |Vtb| = 0.96 ± 0.09 (stat. + syst.) ± 0.05 (theory) and set a lower limit of |Vtb| > 0.78 at the 95% credibility level.Ph.D