Asymptotic freedom: an approach to strong interactions

Politzer.

The discovery of asymptotic freedom has opened up the possibility of extracting new sorts of detailed, dynamical consequences from a strongly interacting quantum field theory. The necessary tools – perturbation theory, the renormalization group, gauge theories, and the operator product expansion – are not new. To anyone familiar with these field theoretic approaches to strong interactions, the novel feature is a simple fact: there is a unique class of theories in which “the origin is an ultraviolet fixed point”. But the consequences are so exciting that it seemed appropriate to review these ideas as they reflect on each other. Many important applications of the renormalization group and the operator product expansion to hadronic physics are omitted; the emphasis here is on recent work based on symptotically free field theories. No doubt, there are some developments so recent that they are not treated in this article. The discussion of the basic results concerning short distance behavior is informal, but, hopefully, accurate and complete. The specific applications are treated in varying detail.