Seminarium Teorii Oddziaływań Elementarnych

n the Standard Model and the most popular Two Higgs Doublet extensions, there are no tree-level flavor changing neutral currents. The reason for this is reviewed, and two other models ("model III" and the BGL model) that do have such currents are discussed. Taking the hints of Higgs decays into mu + tau seriously, it is shown that these models could have large branching ratios of heavy Higgs to mu tau (and in the BGL model, the branching ratio could reach 60%). In addition, these models can have a substantial decay of the charged Higgs into mu + nu_tau, leading to a unique (and, to my knowledge, never studied) signature for a charged Higgs.