Observation of $e^{+}{e}^{-}\to {\pi }^0{\pi }^0{h}_c$ and a neutral charmoniumlike structure $Z_c(4020{)}^0$

M. Ablikim, M. N. Achasov, X. C. Ai +402

Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of $\sqrt{s}=4.23$, 4.26, and 4.36~GeV, we observe $\EE…