Date of this Version
Physical Review D, Volume 2, Number 1, 1 July 1970
It is shown that the ordinary Born approximation for pn and pp̅ charge-exchange scattering correctly accounts for (1) the shape of the forward peak for 0 ≤ (-t) ≤ µ2/2 at PL = 8 GeV/c, and (2) the energy dependence of the cross sections at t=0 in the energy range PL,=2—8 GeV/c. This result is analogous to the well-known success of the electric Born approximation in Π+ 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 Axed pole at a nonsense point of one helicity amplitude aGects another amplitude for which the corresponding point is sense.