Re-analysis of ππ/ KπPhase Shift and Existence of σ$(600) / κ(900)-Particle

Abstract

Re-analyzing the old phase shift data of I=0, ππ(I=1/2, Kπ) scattering, we show an evidence for existence of the σ-particle (κ-particle) with a comparatively light mass, which has been missing for a long time: In the analysis we have applied a new method of interfering Breit-Wigner amplitudes, which makes the scattering amplitude parametrized in terms of only physical quantities, mass and width of resonant particles, in conformity with unitarity. We have introduced phenomenologically a background phase shift δ_{BG} of repulsive core type. The χ^2-fits of the both ππ- and Kπ- phase shifts are improved greatly with the δ_{BG} over the conventional fits without it.

arXiv commentTalk at HADRON'97, the 7th int. conf. on hadron spectroscopy, BNL, August 1997. 4 pages with 3 eps figures