Search for W+t single-top events in the dileptonic channel at ATLAS

We present the results of a search for W-associated (Wt-channel) single top quark production in 7~TeV pp collisions with the ATLAS detector at the LHC. We first select events containing the leptonic decays of two W bosons by requiring two oppositely-charged leptons and significant missing transverse energy. The resulting sample is mostly composed of top pair events, with a small single top contribution. Rectangular cuts variables are then used to isolate the Wt component. After the final selection, we observe 287 data events in 690 1/fb compared with a prediction of 293, in a region with 16% predicted signal purity. We extract the following 95% CL observed(expected) limit on Wt-channel single top quark production: sigma(pp->Wt+x) <39 (41) pb