Rare top decay and CP violation in THDM

We discuss the formalism of the two Higgs doublet model of type III with CP violation from CP-even CP-odd mixing in the neutral Higgs bosons. The flavor-changing interactions among neutral Higgs bosons and fermions are presented at tree level in this type of model. These assumptions allow the study of rare top decays mediated by a neutral Higgs boson; particularly we are interested in t → cl+l-. For this process we estimate the upper bounds of the branching ratios Br(t → cτ+τ-) of the order of 10-9 ∝ 10-7 for a neutral Higgs boson mass equal to 125 GeV and tan β =1, 1.5, 2, 2.5. For the case of t → cτ+τ- the number of possible events is estimated to range from 1 to 10 events, which could be observed in future experiments at LHC with a luminosity of 300 fb-1 and 14 TeV for the energy of the center of mass. Also we estimate that the number of events for the process t → cl+l- in different scenarios is of the order of 2,500. (orig.)