After the great success of perturbative methods in Quantum Field Theory in 1970s, physicists get faced with difficulties of non-perturbative analysis. In same 1970s the concept of supersymmetry appeared. It was realized soon that quantum corrections are controlled by supersymmetry via non-renormalization theorems. The natural idea was, therefore, to use supersymmetric theories as a laboratory for non-perturbative effects, especially for the gauge theories, which are believed to describe Electroweak... Mehr