The decays of a Higgs boson to the $\gamma \gamma$ and $Z\gamma$ final states are purely quantum mechanical phenomena that are closely related to each other. We study the effects of an extended Higgs sector on the decay rates of the two modes. We propose that a simultaneous determination of them and the $ZZ$ mode is a useful way to see whether the Higgs boson recently observed by the LHC experiments is of the standard model type or could be a member of a larger Higgs sector.

• Received 11 July 2012

DOI:https://doi.org/10.1103/PhysRevD.87.033003