Instantons and Wormholes for the Universal Hypermultiplet

In this paper we present supersymmetric instanton and non-supersymmetric wormhole solutions for the universal hypermultiplet sector of $d=4$ N=2 supergravity theories. Instantons and wormholes are constructed as saddle points dominating transition amplitudes between states of definite axionic shift charge, using an approach due to Coleman and Lee. Our solutions are constructed in terms of the conserved Noether charges associated with the global SU(2,1) symmetry of the universal hypermultiplet action. The conditions imposed by regularity on the charges are discussed.