Reaction ${\pi }^{+}p\to {\eta }^0{\Delta }^{++}$: A Test of $A_2$ Regge-Pole Exchange

New results are presented on the reaction ${\pi }^{+}p\to {\eta }^0{\Delta }^{++}$ between 1.2 and $2.67 \frac{\mathrm{GeV}}{c}$. The data above $2 \frac{\mathrm{GeV}}{c}$, when combined with some existing data, give evidence for a dip in the $t$ distribution near $t=-1.5\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right).\mathrm{}}^2$ This dip, and other features of the data, are adequately described by an $A_2$ Regge-pole model. The effective $A_2$ trajectory is calculated and found to disagree with that obtained from the reaction ${\pi }^{-}p\to {\eta }^{0}n$.