WORMHOLES AND BABY UNIVERSES IN SCALAR TENSOR GRAVITY

The existence of euclidean wormhole solutions is demonstrated in two types of scalar-tensor theories of gravity, Brans-Dicke and induced gravity, for the case when the scalar field ψ has a U(1) charge. In both theories the scalar field equations of motion for the modulus φ are independent of the wormhole charge Q so that for constant φ consistent solutions are obtained for arbitrary Q. In Brans-Dicke, when φ varies across the wormhole throat, "lopsided" wormholes result which attach two spaces with different values of the gravitational constant. In induced gravity, wormhole and baby universe solutions are found with φ interpolating between the symmetric and broken phases. These can have finite (through cutoff dependent) action or infinite actiob and can display non-trivial structure for small values of the radial variable. © 1990.