Higher-Derivative Terms in N=2 SUSY Effective Actions
  Harmonic superspace can be used to construct higher derivative terms in N=2 supersymmetric effective actions despite the infinite redundancy in their description due to the infinite number of auxiliary fields. We are able to write down all of the 3- and 4-derivative terms on the Higgs, Coulomb, and mixed branches, modulo the possible existence of superspace Chern-Simons-like terms, which we discuss. Many of the terms we find are holomorphic, and at least one is shown to not receive quantum corrections. 
Philip C. Argyres (1), Adel M. Awad (2), Gregory A. Braun (1), F. Paul   Esposito (1) ((1) University of Cincinnati, (2) Ain...