Search strategies for non-standard Higgs bosons at future e+e− colliders

Abstract

Already in the simplest two-Higgs-doublet model with CP violation in the Higgs sector, the 3×3 mixing matrix for the neutral Higgs bosons can substantially modify their couplings, thereby endangering the “classical” Higgs search strategies. However, there are sum rules relating Yukawa and Higgs– Z couplings which ensure that the ZZ, b b and t t couplings of a given neutral 2HDM Higgs boson cannot all be simultaneously suppressed. This result implies that any single Higgs boson will be detectable at an e + e − collider if the Z+Higgs, b b+ Higgs and t t+ Higgs production channels are all kinematically accessible and if the integrated luminosity is sufficient. We explore, as a function of Higgs mass, the luminosity required to guarantee Higgs boson detection, and find that for moderate tan β values the needed luminosity is unlikely to be available for all possible mixing scenarios. Implications of the sum rules for Higgs discovery at the Tevatron and LHC are briefly discussed.