Interactions ofπ+Mesons with Protons at 2.08BeVc

Interactions of $2.08-\frac{\mathrm{BeV}}{c}$ positive pions with protons have been studied using the 20-in. hydrogen bubble chamber and the alternating gradient synchrotron at Brookhaven National Laboratory. Using 3000 elastic and 8000 inelastic events, the partial cross sections for elastic scattering and for meson production have been measured. The ${\rho }^{+}$, ${\rho }^0$, ${\omega }^0$, and ${\eta }^0$ resonances are produced strongly and emerge predominantly in the forward direction in the center-of-mass system, suggesting a peripheral mechanism for their production. The possibility of explaining these reactions by specific particle-exchange models is investigated. More than 75% of the ${\rho }^0$, ${\omega }^0$, and ${\eta }^0$ are produced with the ${N_{33}}^{*}$ (1238) isobar. The $N^{*}$ (1688) is produced in about one-third of the ${\pi }^{+}{\pi }^{+}N$ final states. Cross sections for production of ${\rho }^{+}p$, ${\pi }^{+}p\omega$, ${N_{33}}^{*}\omega$, ${\pi }^{+}p\eta$, ${N_{33}}^{*}\eta$, ${\pi }^{+}p{\rho }^0$, ${N_{33}}^{*}{\rho }^0$, ${N_{15}}^{*}{\pi }^{+}$, and ${N_{33}}^{*}{\pi }^0$, are given. $A_1$, $B$, $\phi$, and $X$ mesons are not observed.