We consider search strategies for an extended Higgs sector at the
high-luminosity LHC14 utilizing multi-top final states. In the framework of a
Two Higgs Doublet Model, the purely top final states (ttΛ,4t) are
important channels for heavy Higgs bosons with masses in the wedge above
2mtβ and at low values of tanΞ², while a 2b2t final state is most
relevant at moderate values of tanΞ². We find, in the ttΛH
channel, with HβttΛ, that both single and 3 lepton final
states can provide statistically significant constraints at low values of tanΞ² for mAβ as high as βΌ750 GeV. When systematics on the ttΛ
background are taken into account, however, the 3 lepton final state is more
powerful, though the precise constraint depends fairly sensitively on lepton
fake rates. We also find that neither 2b2t nor ttΛ final states
provide constraints on additional heavy Higgs bosons with couplings to tops
smaller than the top Yukawa due to expected systematic uncertainties in the ttΛ background.Comment: Added a Fig. and updated references. Matches journal version. 31
pages, 11 figure