Decays H0--> gamma gamma, gamma Z, and Z--> gamma H0 in the effective Lagrangian approach.

Abstract

We study the decays ${\mathit{H}}^{0}$\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}, \ensuremath{\gamma}Z, and Z\ensuremath{\rightarrow}\ensuremath{\gamma}${\mathit{H}}^{0}$ in the framework of effective Lagrangians. We consider all dimension-six and dimension-eight fermionic and bosonic operators which are ${\mathrm{SU}}_{\mathit{L}}$(2)\ifmmode\times\else\texttimes\fi{}${\mathrm{U}}_{\mathit{Y}}$(1) gauge invariant and contribute to these decays at tree and one-loop level. Our calculations include, besides tree-level contributions, the one-loop contributions in the full theory: standard model and the underlying physics. We find that the effects due to new physics may enhance the standard model widths of these rare decays up to one order of magnitude.