Measurement of the Cross-Section for Producing a W Boson in Association with a Single Top Quark in pp Collisions at √s=13 TeV with ATLAS

The inclusive cross-section for the associated production of a W boson and top quark is measured using data from proton-proton collisions at √s=13 TeV. The dataset corresponds to an integrated luminosity of 3.2 fb⁻¹, and was collected in 2015 by the ATLAS detector at the Large Hadron Collider at CERN. Events are selected requiring two opposite sign isolated leptons and at least one jet; they are separated into signal and control regions based on their jet multiplicity and the number of jets that are identified as containing b hadrons. The W t signal is then separated from the tt̅ background using boosted decision tree discriminants in two regions. The cross-section is extracted by fitting templates to the data distributions, and is measured to be σ_{Wt} = 94 ± 10(stat.){− 22} ^{+ 28} (syst.) ± 2(lumi.) pb. The measured value is in good agreement with the SM prediction of σ{theory} = 71.7±1.8 (scale)± 3.4 (PDF) pb [1].