On low-energy effective action in three-dimensional N = 2 and N = 4 supersymmetric electrodynamics

We discuss general structure of low-energy e-ective actions in N = 2 and N = 4 three-dimensional supersymmetric electrodynamics (SQED) in gauge super-eld sector. There are speci-c terms in the e-ective action having no four-dimensional analogs. Some of these terms are responsible for the moduli space metric in the Coulomb branch of the theory. We -nd two-loop quantum corrections to the moduli space metric in the N = 2 SQED and show that in the N = 4 SQED the moduli space does not receive two-loop quantum corrections.