A search has been made with the Crystal Ball Detector for axionlike particles in radiative $\frac{J}{\Psi }$ decays. An upper limit on the branching ratio $B(\frac{J}{\Psi }\to \gamma +a)<\mathrm{}1.4\mathrm{}\times {10}^{-5\mathrm{}}$ (90% C.L.) is obtained. This result holds for long-lived, noninteracting pseudoscalar or vector particles of mass less than 1 GeV. Thus, this experiment also places stringent limits on the existence of other possible light bosons such as those arising in supersymmetric theories.

• Received 8 February 1982

DOI:https://doi.org/10.1103/PhysRevLett.48.903