A Minimal Model for Dilatonic Gravity

Abstract

We study a new minimal scalar-tensor model of gravity with Brans-Dicke factor $\omega (\Phi )\equiv 0$ and cosmological factor $\Pi (\Phi )$. The constraints on $\Pi (\Phi )$ from known gravitational experiments are derived. We show that almost any time evolution of the scale factor in a homogeneous isotropic Universe can be obtained via properly chosen $\Pi (\Phi )$ and discuss the general properties of models of this type.

Comments: 10 pages, LaTeX, no figures. A new Appendex added, new references, comments and acknowledgments added, typos corrected. Final version: to appear in Modern Physics Letters A