Search for resonant $WZ\to \mathrm{\ell }\nu {\mathrm{\ell }}^{\mathrm{\prime }}{\mathrm{\ell }}^{\mathrm{\prime }}$ production in proton$-$proton collisions at $\sqrt{\mathbf{s}}=\mathbf{13}$ TeV with the ATLAS detector

A search for a $WZ$ resonance, in the fully leptonic final state (electrons and muons), is performed using 139 fb${}^{-1}$ of data collected at a centre-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The results are interpreted in terms of a singly charged Higgs boson of the Georgi$-$Machacek model, produced by $WZ$ fusion, and of a Heavy Vector Triplet, with the resonance produced by $WZ$ fusion or the Drell$-$Yan process. No significant excess over the Standard Model predictions is observed and limits are set on the production cross-section times branching ratio as a function of the resonance mass for these processes.