Observation of the decay $J/\psi \to e^{+}{e}^{-}\eta (1405)$ with $\eta (1405)\to {\pi }^0{f}_0(980)$

BESIII Collaboration, M. Ablikim, M. N. Achasov +612

Using a data sample of $(10087\pm 44)\times 10^6$ $J/\psi$ events collected by the BESIII detector in 2009, 2012, 2018 and 2019, the electromagnetic Dalitz process $J/ψ\to e^+ e^- η(14…