Preliminary results for two pion resonances in D+ and D+s -> π-π+π+ from Fermilab experiment E-791

In this paper the authors present preliminary results of a coherent amplitude analysis of three-pion decays of charm mesons. The analysis includes a greater number of possible resonant states than in previous analyses, and produces masses and Breit-Wigner widths of the isoscalar resonances f0 (980) and f0 (1370) with better precision than previous measurements. They also present preliminary results for the mass and width of the low lying fo (400), sometimes called the σ meson