Nonstrange-Resonance Production inπ+pCollisions at 2.35, 2.62, and 2.90 BeV/c

In an exposure of the Brookhaven National Laboratory 20-in. hydrogen bubble chamber to a separated ${\pi }^{+}$ beam at ${\pi }^{+}$ momenta of 2.35 BeV/c (center-of-mass energy $E^{*}=2.30\mathrm{}$ BeV), 2.62 BeV/c ($E^{*}=2.41\mathrm{}$ BeV), and 2.90 BeV/c ($E^{*}=2.52\mathrm{}$ BeV), we have observed production of the ${\omega }^0$, ${\rho }^0$, and ${\eta }^0$ mesons. The production of the ${\omega }^0$, ${\rho }^0$, and ${\eta }^0$ is often accompanied by simultaneous production of the $N^{*++}$. The momentum transfer in ${\omega }^0$ and ${\rho }^0$ production is characteristic of peripheral collisions and suggests a single-particle exchange for the production mechanism. The decay distributions for the ${\omega }^0$, ${\rho }^0$, and the ${\rho }^{+}$ demonstrate the importance of modifying the single-particle-exchange model to include absorptive effects. An upper limit on the two-$\pi$ decay of the ${\omega }^0$ is set at 2%. The width of the ${\eta }^0$ is found to be less than 10 MeV. Elastic-scattering distributions are presented.