IAS High Energy Theory Seminar

Abstract: Instantons are an important source of nonperturbative effects in quantum field theories, but their role in asymptotically free theories has not been well understood. In this talk, we will present a new approach to instanton analysis in the context of 2d $CP^N$ sigma models.  From this, we will show that, contrary to common belief, instantons can in fact capture the vacuum structure and non-perturbative properties such as mass gap, fractional theta dependence, and confinement. In the supersymmetric sigma model, our method gives a new derivation of the mirror symmetry and the Landau-Ginzburg dual theory. Our construction also demonstrates that there is no conflict between large N and instantons.