Implications of the decay $D_s$→${\pi }^{+}$${\pi }^{\mathrm{-}}$${\pi }^{+}$

The recently observed decay mode $D_s$→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ ${\pi }^{+}$ is studied by incorporating chiral dynamics for the final pions and the experimental observation that the Dalitz plot of ${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ ${\pi }^{+}$ is approximately flat. The sum of the $D_s$→5π decay rates is vanishingly small and the decays into even-number pions are all forbidden. We propose a speculative resonance model to explain the large rate for $D_s$→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ ${\pi }^{+}$ and the absence of $D_s$→ρπ. .AE