An analysis on $$J/\psi \rightarrow \pi ^0\gamma ^*$$ within resonance chiral theory

Abstract In this study, we analyze the first measurement of the electron-positron invariant mass spectrum in $$J/\psi \rightarrow \pi ^0 e^+e^-$$ J / ψ → π 0 e + e - by BESIII, using the framework of resonance chiral theory. Our results indicate that both strong interaction and electromagnetic transition are essential to accurately describe the data. We obtain the $$\pi ^0$$ π 0 transition form factor for $$J/\psi \rightarrow \pi ^0\gamma ^*$$ J / ψ → π 0 γ ∗ and the corresponding decay branching ratios for $$J/\psi \rightarrow \pi ^0 l^+l^-$$ J / ψ → π 0 l + l - . The decay process $$J/\psi \rightarrow \pi ^0 V$$ J / ψ → π 0 V is also examined. It is found that $$J/\psi \rightarrow \pi ^0 \rho ^0$$ J / ψ → π 0 ρ 0 is dominated by the strong interaction, while the other two channels, $$J/\psi \rightarrow \pi ^0 \omega $$ J / ψ → π 0 ω and $$\pi ^0 \phi $$ π 0 ϕ , arise primarily from electromagnetic transitions.