Abstract: |
A 't Hooft loop operator -- the world-line of an infinitely heavy magnetic monopole -- is an order parameter for gauge symmetry breaking, just like a Wilson loop is an order parameter for quark confinement. In supersymmetric gauge theories, we perform an exact calculation of the 't Hooft loop expectation value based on the path-integral approach. The calculation makes full use of supersymmetry, and the path-integral reduces to a geometric analysis of the moduli space of solitons, namely instantons and monopoles. The exact results we obtain for 't Hooft loops confirm the predictions given by two-dimensional conformal field theories, through a recently discovered relation between four- and two-dimensional field theories. |