Charged Higgs boson decays H± → W±(γ, Z) revisited

We study the complete one-loop contribution to H-+/- -> W-+/- V, V = Z, gamma, both in the minimal supersymmetric standard model (MSSM) and in the two Higgs doublet model (2HDM). We evaluate the MSSM contributions and compare them with the 2HDM one, taking into account the B -> X-s gamma constraint, vacuum stability and unitarity constraints in the case of 2HDM as well as experimental constraints on the MSSM and 2HDM parameters. In the MSSM, we found that in the intermediate range of tan beta <= 10 and for large A(t), the branching ratio of H-+/- -> W-+/- Z can be of the order 10(-3) while the branching ratio of H-+/- -> W-+/-gamma is of the order 10(-5). We also study the effects of the CP violating phases of soft SUSY parameters, and found that they can modify the branching ratio by about one order of magnitude. However, in 2HDM where the Higgs sector is less constrained as compared to the MSSM Higgs sector, the branching ratio can be enhanced. For charged Higgs mass of the order 180 - 200 GeV, which can accommodate B -> X-s gamma constraint if one takes into account large theoretical uncertainties, the branching ratio of both modes H-+/- -> W-+/- Z, W-+/-gamma can be of the order 10(-2).