Status of Nucleon Resonances with Masses $M<M_N+M_{\pi }$

Abstract

We discuss different interpretations of peaks observed a few years ago by Tatischeff et al. in missing mass spectra of the reaction $pp->p{i}^{+}pX$, which were declared as new exited nucleon states with small masses. A study of the possible production of such states in the process $\gamma p->p{i}^{+}{N}^{\ast }->p{i}^{+}+\gamma \gamma n$ by analyzing the invariant mass spectrum of $\gamma \gamma n$ is proposed. It is shown that the data, obtained recently at MAMI-B, can allow to analyze this process and to get information about an existence of exited nucleon states with small masses.

Comments: 4 pages, 2 figures, LaTeX with ws-p8-50x6-00.cls. Talk presented at the NSTAR2001 Workshop, Mainz, Germany, March 7-10, 2001