N=2 and N=4 Supersymmetric Low-Energy Effective Actions in Three Dimensions

We study the general structure of superconformal effective actions for N = 2 and N = 4 gauge superfields in the N = 2, d = 3 superspace. Such actions may appear as the low-energy effective actions in various N = 2 and N = 4 supergauge models such as three-dimensional supersymmetric electrodynamics, supersymmetric matter in the gauge superfield background as well as extended SYM and Chern-Simons-matter theories. In particular, for the models of the N = 2 and N = 4 matter in the Abelian gauge superfield background we give the explicit calculations of the low-energy effective actions within the perturbation theory. Dedicated to the 60 year Jubilee of Professor E. Elizalde.