Search for $\eta$ and ${\eta }^{\prime }$ Invisible Decays in $J/\psi \to \varphi \eta$ and $\varphi {\eta }^{\prime }$

M. Ablikim, M. N. Achasov, O. Albayrak +340

Using a sample of $(225.3\pm 2.8)\times 10^6$ $J/\psi$ decays collected with the BESIII detector at BEPCII, searches for invisible decays of $\eta$ and ${\eta }^{\prime }$ in $J/\psi \to \varphi \eta$ and $ϕη…