SCALAR-TENSOR GRAVITATIONAL EFFECTS ON VACUUM DECAY

Motivated by a recently proposed "extended" inflation scenario, we apply the formalism of Coleman and De Luccia to the false-vacuum decay of a scalar field coupled to a scalar-tensor theory of gravity. In particular, we discuss a model for false-vacuum decay of a scalar field minimally coupled in a Brans-Dicke-like theory of gravity. In such theories, the effective gravitational constant is a function of a scalar field. In general, will have nontrivial dynamics in the false vacuum, and as varies the decay rate of the false vacuum need not be constant. We present both an explicit "thin-wall" calculation of the decay rate, and a more general numerical "thick-wall" calculation, comparing them to the standard results for Einstein gravity. We consider some questions of principle concerning boundary conditions for the field. We discuss the consequences of these results for extended models of inflation. © 1990 The American Physical Society.