Abstract
In two-Higgs-doublet models, the vertex () does not occur at the tree level, but is generated at one-loop order. We derive explicit formulas for the contribution of a weak doublet of fermions () to the amplitude in the limit of large fermion masses that appear in the internal loop. In this limit, the amplitude grows as the square of the fermion masses for , and is constant if . In contrast, the amplitude approaches a constant (which depends on ) in the large-fermion-mass limit. Asymptotic results for the contribution of a heavy supersymmetric family are also given. The observability of at a future supercollider requires either and a large -quark mass, or the existence of a fourth-generation nondegenerate quark doublet.
- Received 9 January 1991
DOI:https://doi.org/10.1103/PhysRevD.44.191
©1991 American Physical Society