New four-dimensional black hole solutions of Brans-Dicke equations with a negative constant ω, coupled to a massless scalar field, are presented. The temperature of these black holes is zero and the horizon area is infinite. An astrophysical application is also discussed. Scalar-tensor theories of gravity are considered as the most natural generalizations of general relativity. From theoretical...

We consider a micromaser model to study the influence of Dicke superradiance in the context of the one-atom maser. The model involves a microwave cavity into which twolevel Rydberg atoms are pumped in pairs. We consider a random pump mechanism which allows the presence of at most one pair of atoms in the cavity at any time. We analyze the differences between the present system, called the Dicke...

Gravitational self-interactions are assumed to be determined by the covariant derivative acting on the Riemann-Christoffel field strength. Once imposed on a metric theory, this Yang-Mills gauge constraint extends the equality of gravitational mass and inertial mass to compact bodies with non-negligible gravitational binding energy. Applied to generalized Brans-Dicke theories, it singles out one...