Low-energy effective action of N=2 gauge multiplet induced by hypermultiplet matter

We study the one-loop effective action of the hypermultiplet theory coupled to an external N = 2 vector multiplet. We formulate this theory in an N = 1 superspace and develop a general approach to constructing the derivative expansion of the effective action based on an operator symbol technique adapted to N = 1 supersymmetric field models. The approach under consideration allows us to investigate on a unique ground the general structure of the effective action and to obtain both N = 2 superconformal invariant (non-holomorphic) corrections and anomaly (holomorphic) corrections. The leading low-energy contributions to the effective action are found in explicit farm. (C) 2001 Elsevier Science B.V. All rights reserved.