$A3\mathrm{}$ Region of the Three-Pion Mass Spectrum in the Reaction ${\pi }^{-}p\to p{\pi }^{+}{\pi }^{-}{\pi }^{-}$ at 13 and 20 $\frac{\mathrm{GeV}}{c}$

We report an investigation of the production channels of the $A3\mathrm{}$ region of the ${\pi }^{-}{\pi }^{-}{\pi }^{-}$ mass spectrum from the reaction ${\pi }^{-}p\to p{\pi }^{+}{\pi }^{-}{\pi }^{-}$ at 13 and 20 $\frac{\mathrm{GeV}}{c}$. Evidence that the A3 has a substantial branching ratio to $3\pi$ is obtained; its mass and width are measured as 1658 ± 8 MeV and ${53}_{-16\mathrm{}}^{+20\mathrm{}}$ MeV, respectively. To satisfactorily describe the data an additional peak is required with mass 1830 MeV and width 130 MeV.