Using $14.0\times {10}^6\psi (2S)$ events collected with the BES-II detector, the $C$-parity violating process $J/\psi \to \gamma \gamma$ via $\psi (2S)\to {\pi }^{+}{\pi }^{-}J/\psi$ is studied. We determine a new upper limit for the $J/\psi \to \gamma \gamma$ branching ratio of $\mathcal{B}(J/\psi \to \gamma \gamma )<2.2\times {10}^{-5}$ at the 90% C.L., which is about 20 times lower than the previous measurement.

• Received 6 September 2007

DOI:https://doi.org/10.1103/PhysRevD.76.117101