Measurement of the Associated Production of a Single Top Quark and a W Boson in Single-Lepton Events with the ATLAS Detector

The production of a single top quark in association with a W boson (Wt) is measured with the ATLAS detector using proton-proton collision events with one lepton, three jets and missing transverse energy at √s = 8 TeV. Signal events are identified using an artificial neural network in an unconventional manner, addressing the large uncertainties due to the major background, which has an about 10 times larger cross section and a very similar signature compared with the Wt signal. State-of-the-art statistical methods are used to validate the modelling of the signal and the background, and to extract the cross section for Wt production. The cross section is found to be consistent with related measurements as well as the Standard Model prediction. In addition, a direct measurement of the CKM matrix element Vtb is performed.