PHENOMENOLOGY OF MODELS WITH MORE THAN 2 HIGGS DOUBLETS

We study the most general Multi-Higgs-Doublet Model (MHDM) with Natural Flavor Conservation (NFC). The couplings of a charged scalar H-i(+/-) to up quarks, down quarks and charged leptons depend on three new complex parameters, X(i), Y-i and Z(i), respectively. We prove relations among these parameters. We carry out a comprehensive analysis of phenomenological constraints on the couplings of the lightest charged scalar: X, Y and Z. We find that the general MHDM may differ significantly from its minimal version, the Two-Higgs-Doublet Model (2HDM).