Production and decay mechanism of theBmeson and theωπsystem inπ+pinteractions at 5 GeV/c

The production and decay properties of the $B$ meson are studied in the reaction ${\pi }^{+}p\to \omega {\pi }^{+}p$ at 5 GeV/c, where a cross section of 98±16 μb is found for the final state $p{B}^{+}$. The production angular distribution of the $B^{+}$ shows a forward peak, a possible shoulder at $t^{\prime }\sim 0.25$ Ge${\mathrm{V}}^2$, and a small backward peak. The most likely spin-parity assignment for the $B$ is found to be $1^{+}$, and the $D$-wave fraction in the $B$ decay is ∼ 11%. The differential cross section and density matrix elements of the $B^{+}$ suggest a dominant $\omega$-exchange contribution. The suppression of $A_2$ exchange is also apparent in a study of the reaction ${\pi }^{+}p\to B^0{\Delta }^{++}$. We obtain for $t_{p\Delta }^{\prime }<1\mathrm{}$ Ge${\mathrm{V}}^2$ an estimated cross section of 15±12 μb for $B^0{\Delta }^{++}$ production, which is about 5 times smaller than that of $p{B}^{+}$ at the same $t^{\prime }$ region. The reaction $\pi \pi \to \pi \omega$, extrapolated to the pion pole, is found to yield near the $\pi \omega$ threshold cross sections smaller than previously expected.