Is absorption a consequence of unitarity

Absorptive corrections to scattering and production in a family of explicitly unitary models are studied. We find that in a particular model in which quantum-number constraints are ignored, all the results concerning absorptive corrections found in the Reggeon calculus model of Abramovskii, Kancheli, and Gribov are reproduced. In extended models, however, the effects due to quantum numbers and/or alternative unitarization schemes are shown to have a significant effect on the form of absorptive corrections. In particular, explicitly unitary models are given in which (i) the absorptive corrections enhance all cross sections, and (ii) isospin is introduced in a simple way and is found to produce quite different counting rules from those assumed in the Reggeon calculus. It is shown that the internal quantum-number structure of the Pomeron affects the amount of absorption in inclusive cross sections and hence can be experimentally studied