Table of Contents
Journal of Gravity
Volume 2014, Article ID 625836, 10 pages
http://dx.doi.org/10.1155/2014/625836
Research Article

Study of Antigravity in an Model and in Brans-Dicke Theory with Cosmological Constant

1Department of Theoretical Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
2Polytechnic School, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

Received 23 May 2014; Revised 23 July 2014; Accepted 24 July 2014; Published 17 August 2014

Academic Editor: Cosimo Bambi

Copyright © 2014 V. K. Oikonomou and N. Karagiannakis. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 will 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.