Limited Resurrection of the Born Approximation

It is shown that the ordinary Born approximation for $\mathrm{pn}$ and $p\overline{p}$ charge-exchange scattering correctly accounts for (1) the shape of the forward peak for $0\le \mathrm{}(-t)\mathrm{}\le \frac{{\mu }^2}{2}$ at $P_L=8\mathrm{} \frac{\mathrm{GeV}}{c}$, and (2) the energy dependence of the cross sections at $t=0\mathrm{}$ in the energy range $P_L=2-8\mathrm{} \frac{\mathrm{GeV}}{c}$. This result is analogous to the well-known success of the electric Born approximation in ${\pi }^{+}$ photoproduction. It is then shown that the simplest interpretation of this surprising result within the framework of Regge-pole theory is in terms of the fixed poles which are allowed by unitarity in hadronic amplitudes at certain nonsense points of right signature. Finally, it is shown how such a fixed pole at a nonsense point of one helicity amplitude affects another amplitude for which the corresponding point is sense.