Study of the 6-Pronged π+p Interactions at 5 GeV/c

As a contribution to the study of high-multiplicity phenomena, we have analyzed 3502 six-charged-prong ${\ensuremath{\pi}}^{+}p$ interactions observed in a hydrogen bubble chamber; the incident ${\ensuremath{\pi}}^{+}$ momentum was 5 GeV/c. The total cross section for this multiplicity is $\ensuremath{\sigma}=1.33\ifmmode\pm\else\textpm\fi{}0.05$ mb, mostly contributed by the following reactions: (A) ${\ensuremath{\pi}}^{+}p\ensuremath{\rightarrow}p3{\ensuremath{\pi}}^{+}2{\ensuremath{\pi}}^{\ensuremath{-}}$ (0.40\ifmmode\pm\else\textpm\fi{}0.03 mb), (B) ${\ensuremath{\pi}}^{+}p\ensuremath{\rightarrow}p3{\ensuremath{\pi}}^{+}2{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}$ (0.61\ifmmode\pm\else\textpm\fi{}0.04 mb), and (C) ${\ensuremath{\pi}}^{+}p\ensuremath{\rightarrow}n4{\ensuremath{\pi}}^{+}2{\ensuremath{\pi}}^{\ensuremath{-}}$ (0.11\ifmmode\pm\else\textpm\fi{}0.02 mb). Individual particle momentum distributions, when compared with Lorentz-invariant statistical phase space, display deviations which are rather weak but still quite significant. The ${\ensuremath{\rho}}^{0}$ meson is abundantly produced in the first reaction (0.26\ifmmode\pm\else\textpm\fi{}0.05 mb). In the second reaction the $\ensuremath{\omega}$ meson is seen with a comparable cross section (0.26\ifmmode\pm\else\textpm\fi{}0.03 mb); ${\ensuremath{\chi}}^{0}$ and $\ensuremath{\eta}$ are also observed (50\ifmmode\pm\else\textpm\fi{}20 \ensuremath{\mu}b and 100\ifmmode\pm\else\textpm\fi{}20 \ensuremath{\mu}b, respectively, after correction for neutral decays). For both ${\ensuremath{\rho}}^{0}$ and $\ensuremath{\omega}$ resonances there is indication of spin alignment. ${N}^{*++}(1236)$ production is quite strong; the rate estimate is made difficult by the presence of distortions of the mass spectrum that are shown to be mostly concerned with the ${\ensuremath{\pi}}^{+}p$ combinations of low c.m. velocity. It is suggested that the short lifetime of the ${N}^{*}(1236)$ resonance has some bearing on this effect, which indeed seems to affect also the ${\ensuremath{\rho}}^{0}$ and not the longer-lived $\ensuremath{\omega}$.