Search for the reaction channel $e^{+}{e}^{-}\to \eta \eta J/\psi$ and the isospin partner of the $Z_c(3900)$ at center-of-mass energies $\sqrt{s}=4.226-4.950$ GeV

BESIII Collaboration, M. Ablikim, M. N. Achasov +693

We search for the reaction channel $e^{+}{e}^{-}\to \eta \eta J/\psi$ in a data sample with center-of-mass energies from 4.226 to 4.950 GeV that was collected by the BESIII detector operating a…