Search for the decay $J/\psi \to \gamma +\mathrm{invisible}$

M. Ablikim, M. N. Achasov, P. Adlarson +484

We search for $J/\psi$ radiative decays into a weakly interacting neutral particle, namely an invisible particle, using the $J/\psi$ produced through the process $\psi (3686)\to {\pi }^{+}{\pi }^{-}J/\psi$ in…