Search for the C-parity violating process J/ψ→γγ via ψ(2S)→π+π-J/ψ

Abstract

Using 14.0×106ψ(2S) events collected with the BES-II detector, the C-parity violating process J/ψ→γγ via ψ(2S)→π+π-J/ψ is studied. We determine a new upper limit for the J/ψ→γγ branching ratio of B(J/ ψ→γγ)<2.2×10-5 at the 90% C.L., which is about 20 times lower than the previous measurement. © 2007 The American Physical Society.