Measurement of the Branching Fraction for the Decay $\psi(3686) \rightarrow \phi K_{S}^{0} K_{S}^{0}$

Abstract

Based on $(448.1 \pm 2.9 )\times 10^6$ $\psi(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decay $\psi(3686)\rightarrow \phi K_{S}^{0} K_{S}^{0}$ is observed for the first time. Taking the interference between $\psi(3686)$ decay and continuum production into account, the branching fraction of this decay is measured to be $\mathcal{B}(\psi(3686)\rightarrow\phi K_S^0 K_S^0 )$ = $(3.53 $ $\pm$ $0.20$ $\pm$ $0.21$)$\times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. Combining with the world average value for ${\mathcal B}(J/\psi\to \phi K^0_SK^0_S)$, the ratio $\mathcal{B}(\psi(3686)\rightarrow \phi K_{S}^{0} K_{S}^{0})/\mathcal{B}(J/\psi\rightarrow \phi K_{S}^{0} K_{S}^{0}) $ is determined to be $(6.0\pm 1.6)$%, which is suppressed relative to the 12% rule.