Search for $WW/WZ$ resonance production in the $\ell\nu qq$ final state at $\sqrt{s}=13\,$ TeV with the ATLAS detector at the LHC

A search is presented for new resonances decaying to $WW$ or $WZ$ final states, where one $W$ boson decays leptonically (to an electron or a muon plus a neutrino) and the other $W/Z$ boson decays hadronically. The data analysed comprises 3.2 $\rm{fb}^{-1}$ of $pp$ collision data at $\sqrt{s}=13\,$, TeV recorded with the ATLAS detector at the CERN Large Hadron Collider. No evidence for resonant diboson production is observed, and resonance masses below $1060\,$ GeV and $1250\,$ GeV are excluded at 95% confidence level for a spin-2 Randall-Sundrum bulk graviton and a possible new heavy vector boson coupling to the Higgs and the SM gauge bosons, respectively. The results are also interpreted in the context of an additional Higgs-like boson at high mass.