Mass Terms in Two-Higgs Doublet Models

We take a closer look at the mass terms of all renormalizable and CP conserving two-Higgs doublet models (THDM). We show how some of the dimension two parameters in the potential can be set equal to zero leading to relations among the tree-level parameters of the potential. The different versions of the THDM obtained give rise to different amplitudes for physical processes. We will illustrate this with two examples. The first one is the one-loop weak correction to the top decay width, t -> b W. The second one is the decay h -> gamma gamma in the fermiophobic limit.