Cosmology and Static Spherically Symmetric solutions in D-dimensional Scalar Tensor Theories: Some Novel Features

TL;DR

This paper explores scalar tensor theories in higher-dimensional spacetimes, revealing novel features such as non-singular cosmological solutions and unusual gravitational behavior near horizons.

Contribution

It provides new vacuum solutions in D-dimensional scalar tensor theories, highlighting unique properties like repulsive gravity near horizons for certain functions.

Findings

Cosmological solutions are non-singular for specific functions.

Static solutions exhibit repulsive gravity near horizons.

New features distinguish these solutions from classical models.

Abstract

We consider scalar tensor theories in D-dimensional spacetime, D \ge 4. They consist of metric and a non minimally coupled scalar field, with its non minimal coupling characterised by a function. The probes couple minimally to the metric only. We obtain vacuum solutions - both cosmological and static spherically symmetric ones - and study their properties. We find that, as seen by the probes, there is no singularity in the cosmological solutions for a class of functions which obey certain constraints. It turns out that for the same class of functions, there are static spherically symmetric solutions which exhibit novel properties: {\em e.g.} near the ``horizon'', the gravitational force as seen by the probe becomes repulsive.