S-wave $K^{-}\pi +$ System in $D^{+}\to K^{-}{\pi }^{+}{\pi }^{+}$ Decays from Fermilab E791

Abstract

A new approach to the analysis of three body decays is presented. Model-independent results are obtained for the \swave $K\pi$ amplitude as a function of $K\pi$ invariant mass. These are compared with results from $\Km\pip$ elastic scattering, and the prediction of the Watson theorem, that the phase behavour be the same below $K{\eta }^{\prime }$ threshold, is tested. Contributions from $I=\half$ and $I=\frac{3}{2}$ are not resolved in this study. If $I=\half$ dominates, however, the Watson theorem does not describe these data well.}

Submitted to proceedings of Moriond QCD 2005, La Thuile, March 2005