Symmetries of Regge-Regge cuts

Regge-Regge cuts are shown to satisfy strong symmetry constraints in any model which incorporates Finkelstein's cut selection rule, SU(3) symmetry of Regge residues, and exchange degeneracy of trajectories and residues. These imply, amongst other things, the strong suppression of Regge-Regge cuts in pion-nucleon charge exchange, arising from a cancellation between ϱ-P' and A₂-ω cuts. Therefore if Finkelstein's selection rule is valid, the πN change amplitudes cannot be understood by adding Regge-Regge cuts to an absorbed ϱ pole amplitude.