Search for an isoscalar partner of the $Z_c(3900)$ in $e^{+}{e}^{-}\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}\cdot J/\ddot{I}ˆ$

BESIII Collaboration, M. Ablikim, M. N. Achasov +684

Using a data sample corresponding to an integrated luminosity of 20.3 fb${}^{-1}$ collected at center-of-mass energies from 4.18 to 4.95 GeV with the BESIII detector, we observe the…