Study of the Reactionsπ−p→pπ+π−π−π0andπ−p→nπ+π+π−π−at 8 GeV/c

The reactions ${\pi }^{-}p\to p{\pi }^{+}{\pi }^{-}{\pi }^{-}{\pi }^0$ and ${\pi }^{-}p\to n{\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^{-}$ have been studied at 8 GeV/c. The measured cross sections are 1.39±0.09 and 0.53±0.04 mb, respectively. Resonance parameters and production cross sections are presented for the following resonances produced in the experiment: ${\rho }^0$, ${\rho }^{-}$, ${\rho }^{+}$, $N^{*++}$, ${\omega }^0$, ${\eta }^0$, and $B^{-}$. The final states $p{\omega }^0{\pi }^{-}$ and $N^{*++}$ ${\rho }^{-}{\pi }^{-}$ are studied and the possibility of their production via a double-peripheral mechanism is described. Evidence for the ${\pi }^{+}{\pi }^{-}{\pi }^{-}$ decay modes of the $R\left(1700\right)\mathrm{}$ and $T\left(2200\right)\mathrm{}$ mesons is presented. An enhancement in the ${\pi }^{+}{\pi }^{-}$ effective-mass distribution at 400 MeV is discussed.