GLUEBALL SINGULARITY, FLAVOR LOOPS AND THE HARARI-FREUND PICTURE

We discuss several points concerning the structure of the cylinder term in the dual topological expansion. Using dual field theory as a guide, we concentrate on the possibility of a two-singularity scheme à la Harari-Freund. We start from results obtained previously at the lowest order in ϱ= Nf/Nc and study what can be the role of flavour-loop corrections in the real world where ϱ∼1. It is argued that, in spite of the actual value of ϱ, precise mechanisms exist which can weaken the role of the flavour-loop corrections in the kinematical region where “soft” dynamics dominates. We also claim that the S-matrix at large Nc (ϱ≈-0) incorporates already many realistic features, and we refute some objections recently raised against the Harari-Freund picture. © 1979, Springer-Verlag. All rights reserved.