Six-Prong Interactions ofπ+Mesons with Protons at 8 GeV/c

Final results for 3678 six-prong ${\pi }^{+}p$ events at 8 GeV/c are presented. Single-particle distributions are compared with the predictions of the Chan-$\mathrm{L}$oskiewicz-Allison model and the phenomenological model of the $F\left(t\right)\mathrm{}$ function. Differences between the transverse momenta of the ${\pi }^{+}$ and ${\pi }^{-}$ and between the transverse momenta of secondaries emitted forward and backward in the c.m. system are observed. Cross sections for production of the ${\rho }^0$, ${\rho }^{+}$, ${\rho }^{-}$, $\eta$, ${\omega }^0$, $X^0$, and $D^0$ mesons and the $N_{33}^{*++}$ and $N_{33}^{*-}$ isobars are given, together with upper limits for some other resonances. The $D^0$ meson is observed in the seven-body channel in the $\eta {\pi }^{+}{\pi }^{-}$ system, with some evidence for the cascade decay $D^0\to {\delta }^{\pm }{\pi }^{\mp }\to \eta {\pi }^{+}{\pi }^{-}$. The branching ratio $\frac{(f^0\to 2{\pi }^{+}2{\pi }^{-})}{(f^0\to 2\pi )}$ is determined to be (${2.2}_{-2.2\mathrm{}}^{+4.5\mathrm{}}$)%. Upper limits for the decay of $A$ mesons into $X^0\pi$ systems are quoted. The cross section for the two-body reaction ${\pi }^{+}p\to N_{33}^{*++}{X}^0$ is determined to be 30 ± 13 μb, from which the ${\eta }^0-X^0$ mixing angle is derived. Associated production of $N_{33}^{*++}$ and ${\rho }^0$ in the six-body channel and of $N_{33}^{*++}$, ${\rho }^0$, and ${\omega }^0$ in the seven-body channel is studied, and the cross sections for reactions involving simultaneous production of these resonances are estimated. The Goldhaber-Goldhaber-Lee-Pais effect is studied and shown to be strong in the six-body channel, especially for selected events with low energy of the pion system.