Measurement of $tW$ differential cross-sections with ATLAS at $\sqrt{s}=13$ TeV

The cross-section to produce a $W$ boson in association with a top quark is measured differentially with respect to several particle-level final-state observable quantities. The measurements are performed using 36.1 fb$^{-1}$ of $pp$ collision data at $\sqrt{s}=13$ TeV collected in 2015 and 2016, by the ATLAS detector at the LHC. Cross-sections are measured in a fiducial phase-space defined by the presence of two charged leptons and exactly one jet identified as containing $B$ hadrons. Measurements are normalised to the fiducial cross-section, causing several of the main uncertainties to cancel. The results are found to be in good agreement with predictions from several Monte Carlo generators.