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-\(\gamma Z\) coupling can be measured in the decay \(Z \to \gamma\)+Higgs at \(e^+e^-\) colliders running on the Z resonance, or in the reverse process Higgs \(\to Z \gamma\) 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.