Research of meson spectroscopy

A three-year joint research project (1988-1990), called 'research of meson spectroscopy -- search for quark-antiquark exotics', is under way by the neutral meson search experiment group at CERN, which has been engaged in spectroscopy of meson by means of the GAMS detector, and a Japanese group consisting mainly of members from the High Energy Physics Research Institute. The history of research on quark and gluon is briefly summarized first, and then major features of exotics are described. The GAMS group at CERN has reported that a resonance state of the P wave was detected near an M0 of 1,406 MeV in the decay mode of M0 to η and π0 in the charge exchange reaction π-P → M0n. This could be the first observation of an exotic state involving a gluon. Experiments are now under way in Japan using the 'BENKEI' spectrometer. Data have been collected and analyzed, and results similar to the above ones have been obtained. The present report also describes the data collection and analysis efforts currently being made at CERN and IHEP, and other studies being made for the improvement and development of detection systems. (N.K.)