Search for the decay π0→γX

We present the results of a search for exotic bosons produced in the decay π0→Xγ. A low energy π- beam at TRIUMF was stopped in a liquid hydrogen target to produce the reactions π-p→nγ and π-p→nπ0,π0→γγ. The γ rays from these reactions were detected in a sodium iodide crystal. From the energy distributions we extract a branching ratio limit for Γ(π0→γX)/Γ(π0→γγ) of (2--7)x10-3 for X masses of 25--100 MeV/c2 (90% C.L.). In contrast with other experimental limits this branching ratio limit is valid for all reasonable X lifetimes (>10-23 sec)