Exclusive Signals of an Extended Higgs Sector

Expectations for the magnitude of Higgs boson signals in standard Higgs search channels at the LHC relative to Standard Model (SM) expectations are investigated within the framework of various types of CP and flavor conserving two Higgs doublet models (2HDMs). Signals of the SM-like Higgs boson in different classes of 2HDM may be parameterized in terms of particular two-dimensional sub-spaces of the general four-dimensional space of Higgs couplings to the massive vector bosons, top quark, bottom quark, and tau lepton. We find fairly strong correlations among the inclusive di-photon channel and the exclusive di-photon and di-tau channels from vector boson fusion or associated production. Order one deviations from SM expectations in some of these channels could provide discriminating power among various types of 2HDMs. The ratio of exclusive di-photon to di-tau channels is particularly sensitive to deviations from SM expectations. We also emphasize that deviations from SM expectations in standard Higgs search channels may imply observable signals of non-SM-like Higgs bosons in some of these same channels, in particular in di-photon and di-vector boson channels. The results cataloged here provide a roadmap for interpreting standard Higgs search channels in the context of 2HDMs.