N* Resonances in e+e- Collisions at Bepc

Abstract

$J/\Psi$ particles are abundantly produced at the Beijing Electron Positron Collider (BEPC). The $J/\Psi$ decays provide an excellent place for studying $N^*$ resonances. For $J/\Psi\to\bar NN\pi$ and $\bar NN\pi\pi$, the $\pi N$ and $\pi\pi N$ systems are limited to be pure isospin 1/2 due to isospin conservation. This is a big advantage in studying $N^*$ resonances from $J/\Psi$ decays, compared with $\pi N$ and $\gamma N$ experiments which suffer difficulty on the isospin decomposition of 1/2 and 3/2. All other $N^*$ decay channels which are presently under investigation at CEBAF(JLab, USA), ELSA(Bonn,Germany) and GRAAL(Grenoble, France) with real photon or space-like virtual photon can also be studied at BEPC complementally with the time-like virtual photon. The process $J/\Psi\to\bar NN^*$ or $N\bar N^*$ provides a new way to probe the internal structure of the $N^*$ resonances. The recent results and outlook of our new $N^*$ program at BEPC are presented.