Asymptotic-freedom phenomenology and the Zweig-rule-violating decays of ψ and ψ′

We discuss the Zweig-Iizuka-rule-violating decays of ψ and ψ′ from a phenomenological field theory point of view with effective quark-gluon couplings satisfying asymptotic freedom. This leads to a satisfactory qualitative and quantitative description of those decays. It provides, moreover, an alternative and equivalent approach to the usual strong-interaction approach, based on quark duality diagrams, with which we compare it.