Observation of ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\mu }^{+}{\mu }^{-}$

BESIII Collaboration, M. Ablikim, M. N. Achasov +486

Using $(1310.6\pm 7.0)\times 10^{6}J/\psi$ events acquired with the BESIII detector at the BEPCII storage rings, the decay ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{\mu }^{+}{\mu }^{-}$ is observed for the fir…