Investigations on the Second and Third Resonances in Terms of Compound States

The second and third resonances in pion-nucleon scattering are investigated to see whether the resonance shape can be explained by a new isobaric field (called a compound particle field). Fairly good agreement with experiments has been obtained. To understand the compound particles, we make some speculations by making use of the full symmetry theory for the fundamental baryons of the Sakata. model (the I-O-O theory). Difficulties with respect to the spin assignment of the compound particles by the I-V-O theory are investigated, and a possibility is discussed that the compound particles are bound states of two I-O-O particles. Some analogous features between the system of the Sakata model and the nucleus are also discussed.