Regge Analysis ofπ0andπ+Photoproduction at Backward Angles

By correlating recent experimental results on ${\pi }^0$ and ${\pi }^{+}$ photoproduction at backward angles with results on ${\pi }^{-}p\to p{\rho }^{-}$ at the same angles, it is found that any explanation of the three processes in terms of Regge poles must involve at least two isospin-½ trajectories. Furthermore, the two trajectories must be almost degenerate. Such a solution makes definite predictions about other processes which can be checked by experiments.