Search for single top quark production in pp[over-bar] collisions at [sqrt]s=1.96 TeV in the missing transverse energy plus jets topology

Abstract

We report a search for single top quark production with the CDF II detector using 2.1 fb[superscript -1] of integrated luminosity of p[over-bar p] collisions at [sqrt]s=1.96 TeV. The data selected consist of events characterized by large energy imbalance in the transverse plane and hadronic jets, and no identified electrons and muons, so the sample is enriched in W-->τν decays. In order to suppress backgrounds, additional kinematic and topological requirements are imposed through a neural network, and at least one of the jets must be identified as a b quark jet. We measure an excess of signal-like events in agreement with the standard model prediction, but inconsistent with a model without single top quark production by 2.1 standard deviations (σ), with a median expected sensitivity of 1.4σ. Assuming a top quark mass of 175 GeV/c[superscript 2] and ascribing the excess to single top quark production, the cross section is measured to be 4.9[subscript -2.2][superscript +2.5](stat+syst) pb, consistent with measurements performed in independent data sets and with the standard model prediction.