Study of the electromagnetic Dalitz decays $\psi ({\rm Y})\to {\eta }_c({\eta }_b)l^{+}{l}^{-}$

Li-Min Gu, Hai-Bo Li, Xin-Xin Ma +1

We study the electromagnetic Dalitz (EM) decays, $\psi \to {\eta }_c{l}^{+}{l}^{-}$ and ${\rm Y}\to {\eta }_b{l}^{+}{l}^{-}$ ($l=e$ or $\mu$), in which the lepton pair comes from the virtual photon emit…