Search for $J/\ddot{I}ˆ\to K_S^0{K}_S^0$ and $\ddot{I}ˆ(3686)\to K_S^0{K}_S^0$

Abstract

Using data samples of $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events and $(2712.4\pm 14.3)\times 10^6$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector at the BEPCII collider, we search for the CP violating decays $J/\ddot{I}ˆ\to K_S^0{K}_S^0$ and $\ddot{I}ˆ(3686)\to K_S^0{K}_S^0$. No significant signals are observed over the expected background yields. The upper limits on their branching fractions are set as $\mathcal{B}(J/\ddot{I}ˆ\to K_S^0{K}_S^0)<4.7\times 10^{-9}$ and $\mathcal{B}(\ddot{I}ˆ(3686)\to K_S^0{K}_S^0)<1.1\times 10^{-8}$ at the 90% confidence level. These results improve the previous limits by a factor of three for $J/\ddot{I}ˆ\to K_S^0{K}_S^0$ and two orders of magnitude for $\ddot{I}ˆ(3686)\to K_S^0{K}_S^0$.