Higher-derivative supersymmetric effective field theories

In this paper we study higher-derivative supersymmetric effective field theories focusing on the systematic procedure for the elimination of ghosts from the spectrum. Particular attention is paid to the auxiliary fields, for which the higher-derivative terms induce non-algebraic equations of motion. By employing field redefinitions or the reduction of order procedure (both in component and superfield language) we show that the auxiliary fields remain non-dynamical in the EFT and that on shell they give rise to both derivative and non-derivative corrections to the scalar action. These methods are applied to the search for a SUSY embedding of the DBI action and to the dimensional reduction of HD terms for the K & auml;hler moduli in type IIB string compactifications.