Dalitz plot analysis of Ds+ and D+ decay to π+π-π+ using the K-matrix formalism

FOCUS results from Dalitz plot analyses of D+s and D+ to π+π-π+ are presented. The K-matrix formalism is applied to charm decays for the first time, which allows us to fully exploit the already existing knowledge coming from light-meson spectroscopy experiments. In particular all the measured dynamics of the S-wave ππ scattering, characterized by broad/overlapping resonances and large non-resonant background, can be properly included. This Letter studies the extent to which the K-matrix approach is able to reproduce the observed Dalitz plot and thus help us to understand the underlying dynamics. The results are discussed along with their possible implications for the controversial σ meson