N = 2 supergravity models based on the nonsymmetric quaternionic manifolds. I. Symmetries and Lagrangians

In this paper we consider the N = 2 supergravity models in which the hypermultiplets realize the nonlinear sigma-models, corresponding to the nonsymmetric (but homogeneous) quaternionic manifolds. By exploiting the isometries of appropriate manifolds we give an explicit construction for the Lagrangians and supertransformation laws in terms of usual hypermultiplets in the form suitable for the investigation of general properties of such models as well as for the studying of concrete models.