Speaker
Description
The production of single top quarks occurs via electroweak interaction through three different mechanisms. One of them is the associated production of a top quark and a $W$ boson (the $Wt$-channel). This channel is an excellent probe of the $Wtb$ coupling.
First measurements of $Wt$ production were published by the ATLAS and CMS collaborations, using 2012 data to search for events in which both the $W$ boson and top quark decays include an electron or a muon. The cross-section for the associated production of a single top quark has roughly tripled with the increase in centre-of-mass energy from 8 to \SI{13}{TeV}, making it possible to perform measurements in the $Wt$-channel with the first available LHC datasets at this energy.\
This poster presents a first measurement of the $Wt$ dilepton channel cross-section at \SI{13}{TeV}, using \SI{3.2}{\per\femto\barn} proton--proton collision data taken by ATLAS detector in 2015. The cross-section is extracted by fitting templates to the data distribution, and is measured to be $\sigma_{Wt} = 85.3\pm9(\text{stat.})^{+19}_{-17}(\text{syst.})$. A complementary measurement, showing for the first time, evidence of $Wt$ production in the lepton+jets channel at \SI{8}{TeV} is also presented. Both results are consistent with the respective Standard Model predictions.
