The $\gamma$ parameter in Brans-Dicke-like (light-)Scalar-Tensor theory with a universal scalar/matter coupling and a new decoupling scenario
Abstract
The post-Newtonian parameter resulting from a universal scalar/matter coupling is investigated in Brans-Dicke-like Scalar-Tensor theories where the scalar potential is assumed to be negligible. Conversely to previous studies, we use a perfect fluid formalism in order to get the explicit scalar-field equation. It is shown that the metric can be put in its standard post-Newtonian form. However, it is pointed out that could be either positive, null or negative for finite value of , depending on the coupling function; while Scalar-Tensor theories without coupling always predict for finite value of . Moreover, regardless the value of , the subclass of theories satisfying and surprisingly leads to almost the same phenomenology as general relativity in the solar system.
Keywords
Cite
@article{arxiv.1208.2372,
title = {The $\gamma$ parameter in Brans-Dicke-like (light-)Scalar-Tensor theory with a universal scalar/matter coupling and a new decoupling scenario},
author = {Olivier Minazzoli},
journal= {arXiv preprint arXiv:1208.2372},
year = {2013}
}
Comments
This new version comes form the will of getting clearer. But the discussion on the potential has also been dropped since it is unnecessary for the purpose of the paper (showing that, depending on the scalar/matter coupling function, $1-\gamma$ can be more, equal or less than zero). A particular effort has been made in order to compare the result with previous results based on the string dilaton