Charged Higgs Bosons decays H^\pm \to W^\pm (\gamma, Z) revisited

We study the complete one loop contribution to H^\pm\to W^\pm 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 ones taking into account b\to 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 \la 10 and for large A_t, the branching ratio of H^\pm \to W^{\pm} Z can be of the order 10^{-3} while the branching ratio of H^\pm \to W^{\pm} \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 the 2HDM where the Higgs sector is less constrained as compared to the MSSM higgs sector, one can reach branching ratio of the order 10^{-2} for both modes.