Rare decay H⁺→W⁺γin the minimal supersymmetric standard model

Abstract

The amplitude for the one-loop-induced decay H⁺→W⁺γ is calculated in the 't Hooft-Feynman gauge in the minimal supersymmetric standard model concentrating on the scalar sector only. It is shown that Feynman graphs with gauge bosons, physical and unphysical scalars, and Faddeev-Popov ghosts in the loops undergo large cancellations to contribute negligibly to the final amplitude. The dominant contribution comes from graphs with internal t and b quarks. A numerical evaluation shows that if the charged Higgs boson is lighter than the t quark, then the branching ratio for this process can be as large as ~7×10⁻⁵. For a wide range of parameters, this could remain well within the range of detect- ability at the CERN LHC and SSC.