Double Particle Exchange in Hadronic Reactions

We show that, contrary to present practice and belief, double-particle-exchange contributions to hadronic scattering amplitudes are not negligible. We introduce a hierarchy of exchange mechanisms: (i) Pomeranchon; (ii) single pole exchange (including pole-Pomeranchon cuts), (iii) double particle exchange, etc. The relative strength of any pair of consecutive terms in this hierarchy of amplitudes is of order $\eta ={\eta }_0{\nu }^{\frac{-1\mathrm{}}{2}}$, where ${\eta }_0\sim 0.6$ Be${\mathrm{V}}^{1/2}$. At $\nu =5\mathrm{}$ BeV, double-particle-exchange amplitudes may contribute to 25-50% of the cross section for inelastic processes and should not be ignored.