The Use of Dispersion Relations in the $\pi \pi$ and $K\bar{K}$ Coupled-Channel System

Abstract

Systematic and careful studies are made on the properties of the IJ=00 $\pi \pi$ and $K\bar{K}$ coupled-channel system, using newly derived dispersion relations between the phase shifts and poles and cuts. The effects of nearby branch point singularities to the determination of the $f_0(980)$ resonance are estimated and and discussed.

Comments: 22 pages with 5 eps figures. A numerical bug in previous version is fixed, discussions slightly expanded. No major conclusion is changed