Search for a heavy Higgs boson decaying to a pair of W bosons in proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$

A search for a heavy Higgs boson decaying to a pair of W bosons in the mass range from 200 GeV to 3 TeV is presented. The analysis is based on proton-proton collisions recorded by the CMS experiment at the CERN LHC in 2016, corresponding to an integrated luminosity of $35.9~\mathrm{fb}^{-1}$ at $\sqrt{s}=13~\mathrm{TeV}$. The decay of the W boson pair is reconstructed in the $\ell \nu \ell ' \nu '$ and $\ell \nu q\bar{q}$ final states. Both gluon fusion and vector boson fusion production of the signal are considered, with a number of hypotheses for their relative contribution investigated. Interference effects between the signal and background are also taken into account. Dedicated event categorizations based on the kinematic properties of associated jets and matrix element techniques are employed to optimise the signal sensitivity. The observed data are consistent with the standard model expectation. Combined upper limits at the $95\%$ confidence level on the product of the cross section and branching fraction exclude a heavy Higgs boson with Standard Model-like couplings and decays in the mass range evaluated. Exclusion limits are also set in the context of two Higgs doublet models.