In two-Higgs-doublet models with exact [Formula: see text] symmetry, putting [Formula: see text] at the alignment limit, the following limits on the heavy scalar masses are obtained from the conditions of unitarity and stability of the scalar potential: [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. The constraints from [Formula: see text] and neutral meson mass differences, when superimposed on the unitarity constraints, put a tighter lower limit on [Formula: see text] depending on [Formula: see text]. It has also been shown that larger values of [Formula: see text] can be allowed by introducing soft breaking term in the potential at the expense of a correlation between [Formula: see text] and the soft breaking parameter.
Higgs potential and hidden light Higgs scenario in two Higgs doublet models
