A model for Regge cuts with pole enhancement

Abstract

It is argued that, since hadronic processes show Regge shrinkage even at large ∣ t∣, Regge-cut discontinuities must be enhanced in the region of J near the Regge poles (as suggested by some recent theoretical work on the weak-coupling solution to the “infrared problem” in the reggeon calculus) so that the dominant Regge-cut contribution (at current energies) does not come from the region of the discontinuity near the branch point (as it does in eikonal and absorption models). In particular we show that this hypothesis works well for π −p→ π 0n. However, there is less shrinkage in photoproduction processes at large ∣ t∣, and we find that in γp→ π 0p (and related processes) there is no pole enhancement of the cuts. We connect this fact with the absence of t-channel unitarity constraints for electromagnetic processes and more speculatively with the possibility that a scaling behaviour due to Regge cuts develops at large ∣ t∣ as the mass of the external particle is decreased.