A search for the decay μ+ → e+ γ

Abstract We report on the final analysis of a search for the decay μ + →e + γ performed at SIN. No evidence for the existence of the process has been found. An upper limit for the branching ratio of 1.0 × 10 −9 (90% confidence) is presented. The measured positron-photon energy distributions are completely described by the decay μ + → e + ν e ν μ γ and accidental coincidences.