Heavy Higgs bosons at the LHC upgrade

We evaluate the discovery potential for the heavy Higgs bosons at the LHC energy upgrade with begin{document}$sqrt{s}=27$end{document} TeV. We assume the degenerate mass spectrum and an approximate alignment limit in the Type-II Two Higgs Doublet Model for illustration. We explore the observability of the heavy neutral Higgs bosons by examining the clean signals from begin{document}$H^0to W^+W^-, ZZ$end{document} via gluon-gluon fusion production. The associated production of a top quark and a charged Higgs boson via begin{document}$gbto t H^pm$end{document} is adopted to predict the discovery potential of heavy charged Higgses. We also emphasize the potential importance of the electroweak production of Higgs boson pairs, i.e. begin{document}$ppto W^ast to H^pm A^0$end{document} and begin{document}$ppto Z^ast/gamma^ast to H^+ H^-$end{document}. These are only governed by pure electroweak gauge couplings and can provide complementary information to the conventional signals in the determination of the nature of the Higgs sector.