Observation of Electroweak Single Top-Quark Production with the Cdf Experiment

We present the observation of electroweak single top-quark production using 3.2 fb-1 of data collected by the Cdf experiment. Candidate events are selected for further classification by four parallel analysis techniques: one likelihood discriminant, one matrix-element discriminant, one decision-tree discriminant, and one neural-network discriminant. These outputs are combined with a super discriminant based on a neural-network analysis in order to improve the expected sensitivity. In conjunction with one neural-network discriminant using a complementary dataset we observe a signal consistent with the standard model 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 also present the most current value of the CKM matrix-element Vtb.