Measurement of the cross-section of the production of a $W$ boson in association with a single top quark with ATLAS at $\sqrt{s}=13\,\mathrm{TeV}$

The inclusive production cross-section for the associated production of a $W$ boson and top quark is measured using data from proton--proton collisions at $\sqrt{s}={13}\,\text{TeV}$. The dataset corresponds to an integrated luminosity of $3.2\, \text{fb}^{-1}$, and was collected in 2015 by the ATLAS detector at the Large Hadron Collider at CERN. Events 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 $Wt$ signal is then separated from the $t\bar{t}$ 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 $94 \pm 10\,(\text{stat.})\,^{+28}_{-23}(\text{syst.})$ pb. The measurement is in agreement with the Standard Model prediction.