Search for a new heavy gauge boson resonance decaying into a lepton and missing transverse momentum in 79.8 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment

The results of a search for a new heavy, charged $W^\prime$ boson decaying into an electron or muon and a neutrino using proton-proton collision data at a centre-of-mass energy of $\sqrt{s} = 13$ TeV are presented. The data were collected in 2015, 2016 and 2017 by the ATLAS experiment at the Large Hadron Collider and correspond to an integrated luminosity of 79.8 fb$^{-1}$. As no excess of events above the Standard Model prediction is observed, the results are used to set upper limits on the $W^\prime$ boson cross-section times branching ratio to an electron or muon and a neutrino as a function of the $W^\prime$ mass. Assuming a $W^\prime$ boson with the same couplings as the Standard Model $W$ boson, $W^\prime$ masses below 5.6 TeV are excluded at the 95\% confidence level.