Study of electromagnetic Dalitz decays ${\chi }_{cJ}\to {\mu }^{+}{\mu }^{-}J/\psi$

M. Ablikim, M. N. Achasov, S. Ahmed +449

Using $4.48\times 10^8$ $\psi (3686)$ events collected with the BESIII detector, we search for the decays ${\chi }_{cJ}\to {\mu }^{+}{\mu }^{-}J/\psi$ through the radiative decays $ψ(3686) \r…