Combined fit to the $$e^+e^-\rightarrow \pi ^{+}\pi ^{-}J/\psi $$ e + e - → π + π - J / ψ and $$e^+e^-\rightarrow \pi ^{+}\pi ^{-}\psi (3686)$$ e + e - → π + π - ψ ( 3686 ) line shape
European physical journal. C, Particles and fields