Search for single top quark production in p(p)over-bar collisions at root s=1.96 TeV in the missing transverse energy plus jets topology

Search for single top quark production in p(p)over-bar collisions at root s=1.96 TeV in the missing transverse energy plus jets topology Search for single top quark production in p p collisions at ffiffi ffi s p ¼ 1:96 TeV in the missing transverse energy plus jets topology We report a search for single top quark production with the CDF II detector using 2:1 fb À1 of integrated luminosity of p " p collisions at ffiffi ffi s p ¼ 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 ! 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 (), with a median expected sensitivity of 1:4. Assuming a top quark mass of 175 GeV=c 2 and ascribing the excess to single top quark production, the cross section is measured to be 4:9 þ2:5 À2:2 ðstat þ systÞ pb, consistent with measurements performed in independent data sets and with the standard model prediction.