Observation of the Electromagnetic Dalitz Transition $h_c\to e^{+}{e}^{-}{\eta }_c$

BESIII Collaboration, M. Ablikim, M. N. Achasov +504

Using $(27.12\pm 0.14)\times 10^8$ $\psi (3686)$ decays and data samples of $e^{+}{e}^{-}$ collisions with $\sqrt{s}$ from 4.130 to 4.780~GeV collected with the BESIII detector, we report the…