Search for $H \to WW \to \ell \nu \ell \nu$ Decays of a Heavy Higgs Boson Produced in $pp$ Collisions at $\sqrt {s}$ = 13 TeV Using a 139-fb$^{-1}$ Event Sample Recorded by the ATLAS Experiment

Events with final-state electron and muon pairs produced in pp collisions at $\sqrt s $ = 13 TeV are analyzed toward detecting H → WW → $\ell \nu \ell \nu $ decays of a hypothetical heavy Higgs boson. The analysis relies on the total sample of proton–proton collisions recorded in 2015–2018 by the ATLAS experiment at the LHC, which corresponds to an integrated luminosity of 139 fb$^{−1}$. Through a simulation, selections of signal events are formulated and the control kinematic region for the dominant Drell–Yan background is selected. Expected upper limits on production cross sections of a heavy Higgs boson are estimated under various model assumptions. These upper limits prove to be but slightly inferior to those that can be imposed in the H → WW → $\ell \nu \ell \nu $ decay channel by analyzing events with final-state μe pairs.