Local Coupling and the Supercurrent in Supersymmetric Quantum Field Theory

In order to gain insight into the structure of quantum field theory, one often couples relevant composite operators to external fields such that functional differentiation w.r.t. these fields yields Green functions of the respective operator. A particular variant of this method consists in replacing the coupling constant by a local coupling field. The corresponding composite operator is the local, i.e. non-integrated interaction vertex whose study opens direct access to nonrenormalization theorems [1, 2]. Simultaneously, this operator is related to the supercurrent through the superconformal trace identity, i.e. the conformal anomaly can be written in terms of functional differential operators involving the local coupling. In this article, we mainly concentrate on the case of SQED.