Searching for heavy Higgs bosons in the $t \bar t Z$ and $t b W$ final states

In the context of two-Higgs doublet models, we explore the possibility of searching for heavy Higgs bosons in the $t \bar t Z$ and $t bW$ final states. We develop realistic analyses strategies and in the case of the $t \bar t Z$ channel provide a detailed evaluation of the new-physics reach at the 14 TeV LHC. We find that already with an integrated luminosity of $300 \, {\rm fb}^{-1}$ searches for the $t \bar t Z$ signature can provide statistically significant constraints at low values of $\tan \beta$ for heavy Higgs masses in the range from around $450 \, {\rm GeV}$ to $1150 \, {\rm GeV}$. Future searches for heavy Higgses in the $tbW$ final state are also expected to be able to probe parts of this parameter space, though the precise constraints turn out to depend sensitively on the assumed systematics on the shape of the $t \bar t$ background.