These lectures concern the properties of topological charge in gauge theories and the physical effects which have been attributed to its existence. No introduction to this subject would be adequate without a discussion of the original work of Belavin, Polyakov, Schwarz, and Tyupkin [1], of the beautiful calculation by 't Hooft [2,3], and of the occurrence of 8-vacua [4-6]. Other important topics include recent progress on solutions of the Yang-Mills equation of motion [7,8], and the problem of parity and time-reversal invariance in strong interactions [9] (axions [10,11], etc. ). In a few...

The main task of an experimental talk at a theoreticians school should probably be a tempering one. In this respect, e+e- physics may have been a bad choice. The field has so rapidly developed and dis coveries are chasing each other that much of the optimism of theory has passed over to e+e- experimentalists. A vast amount of experimental material arose from the simple reaction of e+e- annihilation. I, therefore, have to limit myself to recent results - most of them less than one year old. The paper will be organized as follows: In the first lecture (chapter I and II) I will give - a short...

We summarize the situation regarding non-polynomial Lagrangians: I should make the qualification that an enor- mous amount of verification is needed before the problems of renormalizability are all sorted out, but one may ten- tatively state: 1) All matrix elements are finite for theories where the Dyson index D is less than two. 2) For the cases when D=2 or 3, counter-terms have been explicitly written which absorb all infinities and the theories are renormalizable. 3) Mixed theories of polynomial and non-polynomial fields appear to be renormalizable provided the Dyson in- dices separately...

The equations of quantum mechanics, let alone those of quantum field theory, are sufficiently complex to solve that various approximation schemes are both welcome and desirable. In applications to quantum field theory, renorm alized perturbation theory has long been the predominant calculational tool, and it has even tended to shape the entire conceptual outlook on such problems as well. How ever, the apparently irreconcilable conflict between strong interaction physics and perturbation theoretic calculations has given way in the past few years to some fairly revolut ionary (at least for...