Measurement of the ratio of the leptonic widths ${\Gamma }_{ee}/{\Gamma }_{\mu \mu }$ for the $J/\psi$ meson

KEDR Collaboration, V. M. Aulchenko, E. M. Baldin +79

The ratio of the electron and muon widths of the $J/\psi$ meson has been measured using direct $J/\psi$ decays in the KEDR experiment at the VEPP-4M electron-positron collider. The resul…