Search for the radiative transitions $\psi (3770)\to \gamma {\eta }_c$ and $\gamma {\eta }_c(2S)$

M. Ablikim, M. N. Achasov, X. C. Ai +380

By using a 2.92 fb${}^{-1}$ data sample taken at $\sqrt{s}=3.773$ GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions $ψ(3770)\to…