An analysis on J/ψ → π ⁰γ ^* within resonance chiral theory

In this study, we analyze the first measurement of the electron-positron invariant mass spectrum in J/ψ → π 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 π ⁰ π 0 transition form factor for J/ψ → π ⁰γ ^* J / ψ → π 0 γ ∗ and the corresponding decay branching ratios for J/ψ → π ⁰ l⁺l⁻ J / ψ → π 0 l + l - . The decay process J/ψ → π ⁰ V J / ψ → π 0 V is also examined. It is found that J/ψ → π ⁰ ρ ⁰ J / ψ → π 0 ρ 0 is dominated by the strong interaction, while the other two channels, J/ψ → π ⁰ ω J / ψ → π 0 ω and π ⁰ φ π 0 ϕ , arise primarily from electromagnetic transitions.