Two-particle decays of φ resonances and electromagnetic effects
Bazhanov V.V. , Pron'ko G.P., Solov'ev L.D.
A formula is obtained for the cross section of the processes e+e~—*l+l~ in the resonance region; this formula is valid in all orders in the electromagnetic interaction. Its application to ψ resonances makes it possible to determine the resonance parameters.