Determination of the lightest strange resonance K-0*(700) or kappa, from a dispersive data analysis

Abstract

In this work we present a precise and model-independent dispersive determination from data of the existence and parameters of the lightest strange resonance kappa/K-0*(700). We use both subtracted and unsubtracted partial-wave hyperbolic and fixed-t dispersion relations as constraints on combined fits to pi K -> pi K and pi pi -> K (K) over bar data. We then use the hyperbolic equations for the analytic continuation of the isospin I = 1/2 scalar partial wave to the complex plane, in order to determine the kappa/K-0*(700) and K* (892) associated pole parameters and residues.