SATURATING THE BOUND ON THE SCALE OF FERMION MASS GENERATION

Recently, Jager and Willenbrock have shown that the Appelquist and Cha nowitz bound on the scale of top-quark mass generation can formally be saturated at tree-level in a particular Limit of a two-Higgs doubler model. In this note I present an alternate derivation of their result. I perform a coupled channel analysis for f (f) over bar, VLVL and VLV L --> VLVL scattering and derive the conditions on the parameters requ ired for f (f) over bar, VLVL scattering to be relevant to unitarity. I also show that it is not possible to saturate the bound on fermion m ass generation in a two-Higgs model while maintaining tree-level unita rity in Higgs scattering at high energies. (C) 1998 Elsevier Science B .V. All rights reserved.