Observation of the Decay $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}{K}_{S}^{0}{K}_{L}^{0}$

Observation of the Decay $ψ (2 S) \to K_{S}^{0} K_{L}^{0}$

J. Z. Bai et al. (BES Collaboration)

Phys. Rev. Lett. 92, 052001 – Published 5 February 2004

Abstract

The decay $ψ (2 S) \to K_{S}^{0} K_{L}^{0}$ is observed using $ψ (2 S)$ data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be $B (ψ (2 S) \to K_{S}^{0} K_{L}^{0}) = (5.24 \pm 0.47 \pm 0.48) \times 10^{- 5}$ . Compared with $J / ψ \to K_{S}^{0} K_{L}^{0}$ , the $ψ (2 S)$ branching fraction is enhanced relative to the prediction of the perturbative QCD “12%” rule. The result, together with the branching fractions of $ψ (2 S)$ decays to other pseudoscalar meson pairs ( $π^{+} π^{-}$ and $K^{+} K^{-}$ ), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of $ψ (2 S)$ decays.