The Higgs - photon - Z boson coupling revisited

Abstract

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.

Comments: 18 pages LaTex + 7 figures (ps). Typo corrected in eq.(5)