An analysis on J/ ⁰ ^* within resonance chiral theory

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