Study of three quasi-two-body channels fromπ+pinteractions at 3.9 GeV/c

Abstract

The $p{\pi }^{+}{\pi }^0$ and $p{\pi }^{+}{\pi }^{+}{\pi }^{-}$ final states from ${\pi }^{+}p$ interactions at 3.9 GeV/c have been analyzed by the prism-plot technique and the following three quasi-two-body channels have been studied in detail: ${\pi }^{+}p\to {\rho }^{+}p$, ${\pi }^{+}p\to {\pi }^0{\Delta }^{++}$, and ${\pi }^{+}p\to {\rho }^0{\Delta }^{++}$. Results are presented on cross sections, differential cross sections, and single and joint spin density matrix elements. These are compared with the Dar-Watts-Weisskopf absorption model and Reggeized pion-exchange model predictions. Relations among joint spin density matrix elements for ${\rho }^0{\Delta }^{++}$ are compared with quark-model predictions.