Neutral and charged Higgs detection. Heavy quark fusion, top quark mass-dependence and rare decays

We examine the relevance of heavy quark fusion processes for production of both neutral and charged Higgs bosons. Top quark mass-dependence of these mechanisms as well as of gg fusion production of the neutral Higgs is explored. We find that gg fusion is generally larger than tt fusion for the neutral Higgs and even dominates WW/ZZ fusion in the region m_H⁰ ≤ 1 TeV for top masses above m_t = 150 GeV. For charged Higgs boson production via tb fusion, the rate may be sufficiently large to permit its detection by making use of the H⁺ → τ⁺ ν_τ decay mode; other distinctive final states, available in supersymmetric models, are also considered. Finally, we show that backgrounds to heavy quark fusion subprocesses can be reduced by tagging on a lepton emitted from the accompanying spectator t-quark.