Regge-Pole Analysis ofpn→npandpp¯→nn¯Scattering

The differential cross sections for the reactions $\mathrm{pn}\to \mathrm{np}$ and $p\overline{p}\to n\overline{n}$ have been investigated. It is found that besides the $\rho$ and $R\left(A_2\right)$ trajectories, the $\pi$ and $B$ trajectories must be included. A variety of schemes suggested by four-dimensional symmetry have been investigated. The existence of various daughter trajectories does not suffice to explain the data, though the data can be fitted with a parity doublet, of which the pion may or may not be a member. In the former case some structure must be introduced into the pion residue function.