Instantons beyond topological theory II

Understand

The present paper is the second part of our project in which we describe quantum field theories with instantons in a novel way by using the "infinite radius limit" (rather than the limit of free field theory) as the starting point.

• The theory dramatically simplifies in this limit, because the correlation functions of all, not only topological (or BPS), observables may be computed explicitly in terms of integrals over finite-dimensional moduli spaces of instanton configurations.
• In Part I (arXiv:hep-th/0610149) we discussed in detail the one-dimensional (that is, quantum mechanical) models of this type.
• Here we analyze the supersymmetric two-dimensional sigma models and four-dimensional Yang--Mills theory, using the one-dimensional models as a prototype.