We obtain static and rotating electrically charged black holes of a Einstein-Maxwell-Dilaton theory of the Brans-Dicke type in (2+1)dimensions. The theory is specified by three fields, the dilaton φ, the graviton gμν and the electromagnetic field Fμν , and two parameters, the cosmological constant Λ and the Brans-Dicke parameter ω. It contains eight different cases, of which one distinguishes a...

The formulation of Brans-Dicke (BD) gravity with matter in the Einstein frame is realized as Einstein gravity with dilaton and dilaton coupled matter. We calculate the one-loop 4d anomaly–induced effective action (EA) due to N dilaton coupled massless fermions on the time dependent conformally flat background with non-trivial dilaton. Using such (complete) effective action, the (fourth-order) q...

We develop a new model of a spinning particle in Brans-Dicke space-time using a metric-compatible connection with torsion. The particle's spin vector is shown to be Fermi-parallel (by the Levi-Civita connection) along its worldline (an autoparallel of the metric-compatible connection) when neglecting spin-curvature coupling.

In a Brans-Dicke (BD) cosmological model, the energy density associated with some scalar field decreases as a −2 ( ωo+ 1 2 ωo+1 ) with the scale factor a(t) of the Universe, giving a matter with an Equation of state p = − 1 3 (

We study the Brans-Dicke model in the presence of an axion. The dynamical equations are solved when the fields are space independent and the metric is spatially flat. It is found that at late time the scale factor undergoes decelerated expansion but the dilaton grows large. At early time, scale factor and the dilaton approach constants.

The gravitational fields of vacuumless global and gauge string have been studied in Brans-Dicke theory under the weak field assumption of the field equations. It has been shown that the global vacuumless string has a repulsive gravitational effect whereas the gauge string has an attractive gravitational effect in BD theory.

A specific choice of gauge is shown to imply a decoupling between the tensor and scalar components of Gravitational Radiation in the context of Brans-Dicke type theories of gravitation. The comparison of the predictions of these theories with those of General Relativity is thereby made straightforward.

Linearized gravitational waves in Brans-Dicke and scalar-tensor theories carry negative energy. A gauge-invariant analysis shows that the background Minkowski space is stable at the classical level with respect to linear scalar and tensor inhomogeneous perturbations. PACS: 04.20.Cv, 04.30.-w

We use the technique of conformal transformations to generate self-similar collapse in Brans-Dicke theory. We analyze the solutions concerning the critical behavior found recently by Choptuik. The critical exponent associated to the formation of black hole for near critical evolution is obtained. The role of the coupling parameter is discussed.