kappa Particle in the Analysis of the BESII Data and Chiral sigma Nonet

Abstract

The observation of the scalar meson, kappa(900) was reported in the fall of the last year in the analyses on the K pi system of the J/psi -> bar K^*(892)^0 K^+ pi^- decay data obtained by the BES collaboration. The analyses have been performed by two groups of the collaboration. The results obtained in the both analyses are in good agreement. They are also in good agreement with those obtained in the analysis of D^+ -> K^- pi^+ pi^+ decay by the E791 experiment. The evidence for the existence of the kappa(900) particle in the production process as well as in the scattering process confirms the scalar sigma nonet with that of sigma(600), firmly. It may be the chiral scalar sigma nonet which is the chiral partner of the pi nonet. Here, the essential points of the analysis of kappa(900) in the BES J/psi decay data, a brief review on present status of the observation of sigma(600) and kappa(900) and also the chiral scalar sigma nonet are presented. It is also tried to summarize the relation between the pi pi (K pi) scattering and the production amplitudes, relating with comments which were presented in the course of studies of the sigma(600) and the kappa(900) particles. The comments concern with the apparent differences between the pi pi (K pi) scattering phase shift data and the mass spectra of the pi pi (K pi) system in the production processes observed experimentally.