Light mesons and charm decays: New results from E791
  We will discuss how the decays of charm mesons can be used to study light mesons spectroscopy, by presenting recent results of Dalitz plot analyses using data from Fermilab experiment E791. Emphasis will be on scalar mesons, which are found to have large contribution to the $D$ decays studied. In addition to the usual extraction of decay fractions and relative phases of the intermediate amplitudes, the Dalitz plot technique is used to measure masses and widths of scalar resonances. From the $D_s$ decay, we obtain masses and widths of $f_0(980)$ and $f_0(1370)$. We find evidence for a light and broad scalar resonance, the $\sigma$ meson, in $D^+\to\pi^-\pi^+\pi^+$ decay. Preliminary studies also show evidence for a light and broad resonance, the $\kappa$ meson, in $D^+\to K^-\pi^+\pi^+$ decay. These results illustrate the potential of charm decays as a laboratory for the study of light mesons. 
Carla Gobel (for the E791 Collaboration)