Determination of the Lightest Strange Resonance K 0 ( 700 ) or κ , from a Dispersive Data Analysis

In this work we present a precise and model-independent dispersive determination from data of the existence and parameters of the lightest strange resonance κ / K0* ( 700 ) . We use both subtracted and unsubtracted partial-wave hyperbolic and fixed- t dispersion relations as constraints on combined fits to πK → πK and ππ → K K ¯ 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 κ / K0* ( 700 ) and K* ( 892 ) associated pole parameters and residues.