Dynamical supressions from dual models

It is shown that dual models naturally account for experimentally observed dynamical suppressions and narrow resonance effects, part of which are conventionally interpreted by means of the Zweig-Iizuka rule. Predictions from two specific dual schemes are discussed. i) The linear zero bootstrap, suggested by the data to hold in spin independent amplitudes, which turns out to provide a unified explanation for a large variety of suppression effects experimentally affecting conventional resonances. ii) The generalized Veneziano model, which, in spite of its strong physical limitations, appears to contain a built-in expectation for psi-type effects in its folds, and moreover provides a consistent understanding of the associated experimental features observed in electron-positron annihilation. (author)