Are regge cuts still worthwhile?

Abstract

In this review first the considerable internal flexibility of Regge-cut models is emphasized. In order to reduce this flexibility, popular Regge-cut models (especially Argonne, Michigan) are confronted with a set of theoretical and decisive experimental constraints, the most important ones being the dual absorptive picture of Harari for the dip systematics and the new polarization data of πN-charge exchange. In general it is concluded that all current Regge-cut models are seriously affected by the set of constraints — even in the case of the “unproblematic” class of hadronic reactions, dominated by vector and tensor exchange. In particular the following results were found: i) the real parts of the helicity-nonflip amplitudes are wrong, i.e. by far too much absorbed, in the Michigan as well as in the Argonne model; moreover in the Michigan model the real parts of the helicity-flip amplitudes are wrong, too, ii) there is much support for wrong signature nonsense zeros in the Regge-pole input and iii) the correct crossover of elastic differential cross sections does not necessarily imply very strong absorption. Altogether a weak cut type model — if any — seems to be favoured for the imaginary parts of the amplitudes. The real parts should then be calculated from fixed t-dispersion relations.