The Higgs–photon–Z boson Coupling Revisited

We analyze the coupling of CP-even and CP-odd Higgs bosons to a photon and a Z boson in extensions of the Standard Model. In particular, we study in detail the effect of charged Higgs bosons in two–Higgs doublet models, and the contribution of SUSY particle loops in the minimal supersymmetric extension of the Standard Model. The Higgs–γZ coupling can be measured in the decay Z → γ+Higgs at e+e− colliders running on the Z resonance, or in the reverse process Higgs → Zγ with the Higgs boson produced at LHC. We show that a measurement of this coupling with a precision at the percent level, which could be the case at future e+e− colliders, would allow to distinguish between the lightest SUSY and standard Higgs bosons in large areas of the parameter space.