Lectures on 2D Yang-Mills Theory, Equivariant Cohomology and Topological   Field Theories
  These are expository lectures reviewing   (1) recent developments in two-dimensional Yang-Mills theory, and   (2) the construction of topological field theory Lagrangians. Topological field theory is discussed from the point of view of infinite-dimensional differential geometry. We emphasize the unifying role of equivariant cohomology both as the underlying principle in the formulation of BRST transformation laws and as a central concept in the geometrical interpretation of topological field theory path integrals. 
Stefan Cordes, Gregory Moore, and Sanjaye Ramgoolam