Realistic extremely flat scalar potential in 3 - 3 - 1 models

We show that in 3-3-1 models an extremely flat and realistic scalar potential i.e., accommodate a tiny, or even zero, contribution to the cosmological constant and still having realistic values of the Higgs scalar mass spectra can be implemented. When loop corrections are considered, they impose constraints on the masses of other heavy particles present in the model. We also consider, at the tree level, the multi-Higgs extensions of the standard model, i.e., twoHiggs doublets model with and without supersymmetry. A crucial ingredient in 3-3-1 models is the existence of trilinear terms in the scalar potential. PACS numbers: 12.60.-i Models beyond the standard model 12.80.Cp Non standard-model Higgs boson 98.80.Es Observational cosmology (including Hubble constant, distance scale, cosmological constant, early Universe, etc) Typeset using REVTEX 1