Search for KS0 invisible decays

Abstract

Based on (1.0087 ± 0.0044) × 10¹⁰J/ψ events collected with the BESIII detector at the BEPCII e⁺e⁻ storage ring, we search for $K_S^0$ invisible decays via the J/ψ →$\varphi K_S^0{K}_S^0$ process. No significant signal is observed, and the upper limit of the branching fraction of these invisible decays is set at 8.4 × 10⁻⁴ at the 90% confidence level. This is the first experimental search for $K_S^0$ invisible decays.