Search for direct chargino pair production with W-boson mediated decays in events with two leptons and missing transverse momentum at $\sqrt{s} = 13$ TeV with the ATLAS detector

The results of a search for the direct pair production of charginos decaying via W-bosons are reported using 80.5 fb-1 of integrated luminosity from LHC $pp$ collisions at 13 TeV collected by the ATLAS detector in the 2015, 2016 and 2017 data taking campaigns. Charginos are searched for in final states with two isolated leptons (electron or muon), missing transverse momentum and at most one light jet in the final state. No excess above Standard Model expectations is observed. Exclusion limits are derived on the chargino mass assuming a simplified model in which it decays with a 100% branching ratio to an on-shell W-boson and the lightest neutralino: $\tilde{\chi}_1^\pm \rightarrow W^\pm \tilde{\chi}_1^{0}$. For a massless neutralino, chargino masses up to 410~GeV are excluded at 95% confidence level.