Search for the decayK+→π+γγ

A search for decays of the form ${\mathit{K}}^{+}$→${\mathrm{\pi }}^{+}$γγ was performed for pion kinetic energies between 117 and 127 MeV. A 90%-C.L. upper limit for the branching ratio of B(${\mathit{K}}^{+}$→${\mathrm{\pi }}^{+}$γγ)<1.0×${10}^{\mathrm{-}6}$ is set for direct decays assuming a ${\mathrm{\pi }}^{+}$ energy distribution given by phase space. Limits are set for decays of the type ${\mathit{K}}^{+}$→${\mathrm{\pi }}^{+}$ ${\mathit{X}}^0$, ${\mathit{X}}^0$→γγ, where ${\mathit{X}}^0$ is any short-lived neutral particle with mass smaller than 100 MeV/${\mathit{c}}^2$.