Localization for Wilson Loops in Chern-Simons Theory

We reconsider Chern-Simons gauge theory on a Seifert manifold M, which is the total space of a nontrivial circle bundle over a Riemann surface, possibly with orbifold points. As shown in previous work with Witten, the path integral technique of non-abelian localization can be used to express the partition function of Chern-Simons theory in terms of the equivariant cohomology of the moduli space of flat connections on M. Here we extend this result to apply to the expectation values of Wilson loop operators which wrap the circle fibers of M. Under localization, such a Wilson loop operator reduces naturally to the Chern character of an associated universal bundle over the moduli space. Along the way, we demonstrate that the stationary-phase approximation to the Wilson loop path integral is exact for torus knots, an observation made empirically by Lawrence and Rozansky prior to this work.