ETA-NUCLEUS INTERACTION STUDIES: EXPERIMENTAL EFFORTS

Abstract

The idea that the η meson could form a bound system with nucleus was put forward long ago by Q.Haider and L.C.Liu and was based on the observation that the low energy η-nucleon interaction was attractive. Since then a number of theoretical calculations have been performed to the predict eta-nucleus bound states. Such bound states-the so called "eta-mesic nuclei" - are predicted to have finite widths and will eventually decay. The experimental confirmation of such a quasi-bound system would be a very useful tool for investigation of interaction between a short lived eta-meson and the nucleus. Since the eta-mesons can not be produced as a secondary beam, the eta-meson particles are available for investigations only as products of certain nuclear reactions where they appear as final state particles. The final state interaction(FSI) effects are the only source of information about the eta-meson interaction with the nucleus. Experiments were performed at the cooler synchrotron accelerator, COSY, Juelich using dedicated detection systems to study the eta-nucleus interaction. The present talk summarizes the status of previous experimental searches. Some preliminary results of the experiments performed at COSY on the eta-nucleus FSI studies are also presented here. The details of the experiments done at COSY, Juelich on eta-mesic nuclei searches along with recent results are reported in an another communication in this proceedings.