4-DIMENSIONAL GRAVITATIONAL BACKGROUNDS BASED ON N=4, (C)OVER-CAP=4, SUPERCONFORMAL SYSTEMS

We propose two new realizations of the N = 4, (c) over cap = 4 superco nformal system based on the compact and noncompact versions of parafer mionic algebras. The target space interpretation of these systems is g iven in terms of four-dimensional target spaces with non-trivial metri c and topology different from the previously known four-dimensional se mi-wormhole realization. The proposed (c) over cap = 4 systems can be used as a building block to construct perturbatively stable superstrin g solutions with covariantized target space supersymmetry around non-t rivial gravitational and dilaton backgrounds.