A discussion is given of the mechanisms by which a light scalar or pseudoscalar boson, such as a familon, may be emitted in the radiative decay of a muon. The results of a new experimental search for the decay ${\mu }^{+}$→$e^{+}$γf, where f is such a boson, are presented. The resulting bounds on the coupling strength are comparable to, but of wider validity than, those from ${\mu }^{+}$→$e^{+}$f. .AE

• Received 16 March 1987

DOI:https://doi.org/10.1103/PhysRevD.36.1543