Exact electric-magnetic duality in N=2 supersymmetric QCD theories

We analyze the Coulomb phase of theories of N = 2 SQCD with SU(N-c) gauge groups which are conjectured to have exact electric-magnetic duality. We discuss the duality transformation of the particle spectrum, emphasizing the differences between the general case and the SU(2) case. Some difficulties associated with the definition of the duality transformation for a general gauge group are discussed. We compute the classical monopole spectrum of these theories, and when it is possible we use it to check the consistency of the duality. Generally these theories may have phase transitions between strong and weak coupling, which prevent the semi-classical computation from being useful for checking the duality.