New experimental upper limit for the decay K/sup + -/. -->. pi pi. /sup + -/. gamma gamma. [Branching ratio; phase-space model]

We have searched for the rare decay mode K/sup plus-or-minus/ ..-->.. ..pi../sup plus-or-minus/..gamma gamma.. using scintillation counters, optical spark chambers, and a wire-spark-chamber spectrometer. After background subtraction we obtain a branching ratio of (-4.2 +- 5.2) x 10/sup -5/. The result is somewhat model-dependent. The quoted branching ratio, which comes from a fit to the phase-space model, is the highest value obtained from the various models considered. (AIP)