Search for invisible decays

Based on (1$\textit{.}$0087 $\textit{±}$ 0$\textit{.}$0044) $\textit{×}$ 10 $\textit{J/ψ}$ events collected with the BESIII detector at the BEPCII $\textit{e}$ $\textit{e}$ storage ring, we search for invisible decays via the $\textit{J/ψ →}$ process. No significant signal is observed, and the upper limit of the branching fraction of these invisible decays is set at 8.4 $\textit{×}$ 10 at the 90% confidence level. This is the first experimental search for invisible decays.