Search for $K_S^0$ invisible decays

Abstract

Based on $(1.0087\pm 0.0044)\times 10^{10}$ $J/\ddot{I}ˆ$ events collected with the BESIII detector at the BEPCII $e^{+}{e}^{-}$ storage ring, we search for $K_S^0$ invisible decays via the $J/\ddot{I}ˆ\to \ddot{I}•K_S^0{K}_S^0$ process. No significant signal is observed, and the upper limit of the branching fraction of these invisible decays is set at 8.4 $\times$ $10^{-4}$ at the 90\% confidence level. This is the first experimental search for $K_S^0$ invisible decays.