The branching ratio of $J/\overrightarrow{\psi }{K}_S^0{K}_L^0$ is measured with improved precision to be $\mathcal{B}(J/\overrightarrow{\psi }{K}_S^0{K}_L^0)=(1.82\mathrm{}\pm 0.04\pm 0.13)\times {10}^{-4}$ using $J/\psi$ data collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider. This result is used to test the perturbative QCD prediction between $\psi \mathrm{}\left(2S\right)\mathrm{}$ and $J/\psi$ decays and to investigate the relative phase between the three-gluon and one-photon annihilation amplitudes in $J/\psi$ decays.

• Received 13 October 2003

DOI:https://doi.org/10.1103/PhysRevD.69.012003