GP Seminar: The 3d A-model, Seifert manifolds and generalised symmetries

Abstract: The 3d A-model is a two-dimensional topological field theory approach to the computation of supersymmetric partition functions and other half-BPS observables of 3d N=2 supersymmetric gauge theories; it is also known as the Bethe-vacua approach. It is a powerful method of computation of supersymmetric partition functions on generic Seifert three-manifolds, including the most studied examples of the 3-sphere partition function and of the topologically twisted index. We revisit this approach in the presence of topological operators for a discrete one-form symmetry. In particular, we study the gauging of one-form symmetries, which allows us to discuss theories with simple gauge groups which are not simply-connected — for instance, an SO(3) gauge theory instead of an SU(2) gauge theory. We will revisit (supersymmetric) pure Chern—Simons theories as an instructive class of examples throughout.

This is a seminar in the Centre of Geometry and Physics seminar series.