Speaker
Description
Recent BESIII measurement of $J/\psi \to e^+e^-\pi^0$ has revealed a significant $\rho$-$\omega$ interference pattern in the di-electron invariant mass spectrum. This observed pattern is qualitatively similar to that of the pion form factor but features a relatively narrow $\rho$ resonance. Motivated by this observation, we present updated Vector Meson Dominance (VMD) predictions for the rare electromagnetic Dalitz decays $\psi \to \ell^+\ell^-\pi^0$ (where $\psi = J/\psi, \psi(2S)$ and $\ell = e, \mu$). By including $\rho$-$\omega$ interference contributions, the updated branching fraction predictions are significantly enhanced. Our results indicate that the decay mode $J/\psi \to \mu^+\mu^-\pi^0$ could be observable at BESIII, while $\psi(2S) \to \ell^+\ell^-\pi^0$ decays are within reach of the proposed Super Tau-Charm Factory (STCF) experiment.
