Study ofπ+pFour-Prong Interactions from 2.95 to 4.08 GeV/c

In a study of the production mechanism of quasi-two-body final states at the five incident ${\pi }^{+}$ momenta 2.95, 3.2, 3.5, 3.75, and 4.08 GeV/c, approximately 40 000 events with four outgoing charged particles were investigated. The cross sections for the processes ${\pi }^{+}p\to N^{*++}\rho$, ${\pi }^{+}p\to N^{*++}\omega$, ${\pi }^{+}p\to N^{*++}\eta$, and ${\pi }^{+}p\to N^{*++}f$ have been measured as a function of the pion energy. The differential cross sections and the decay density-matrix elements are discussed in terms of one-meson-exchange models [with absorption (OPEA) and with form factor (OPEW)] and Regge models. For the $N^{*++}\rho$ and the $N^{*++}\omega$ reactions, the joint-decay matrix elements are calculated. The formation of $N^{*}\mathrm{}\left(2850\right)\mathrm{}$ in the direct channel is also investigated.