Study of Antigravity in an F(R) Model and in Brans-Dicke Theory with Cosmological Constant
arXiv:1408.0398
Abstract
We study antigravity, that is having an effective gravitational constant with a negative sign, in scalar-tensor theories originating from -theory and in a Brans-Dicke model with cosmological constant. For the theory case, we obtain the antigravity scalar-tensor theory in the Jordan frame by using a variant of the Lagrange multipliers method and we numerically study the time dependent effective gravitational constant. As we shall demonstrate by using a specific model, although there is no antigravity in the initial model, it might occur or not in the scalar-tensor counterpart, mainly depending on the parameter that characterizes antigravity. Similar results hold true in the Brans-Dicke model.
Invited letter from Journal of Gravity, to appear