Further Analysis on σ-particle Properties

Abstract

In a previous work, we have reanalyzed the I=0 S-wave ππ-scattering phase-shift through a new method of Interfering Breit-Wigner amplitudes, and have shown the existence of a light scalar, σparticle, accompanied by a negative "repulsive core"-type background phase-shift, whose origin may have some correspondence to a ``compensating'' ππcontact interaction. In this work we make further analysis on the phase shift under KKbar threshold from the same standpoint, to determine precise values of σmass and width, so far as present experimental data are concerned.