,
the model violates unitarity,
unless some of the Higgs bosons are heavy. In the regime of large CP violation
in the neutral-Higgs-t-quark sector, which requires tan
, the
Yukawa coupling parameter space (determined by the neutral-Higgs-sector
rotation matrix) is reasonably unconstrained. On the other hand, the
corresponding neutral-Higgs-b-quark sector allows for large CP violation at
tan 
.
However, here the model is more constrained: Significant CP
violation is correlated with a considerable splitting among the two heavier
Higgs bosons.
Key words: vacuum stability, two-Higgs-doublet model, CP violation, unitarity
