Measurement of the leptonic decay width of $J/\psi$ using initial state radiation

BESIII Collaboration, M. Ablikim, M. N. Achasov +414

Using a data set of 2.93 fb${}^{-1}$ taken at a center-of-mass energy of $\sqrt{s}$ = 3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process $e^+e^-\righta…