Bouncing Universes in Scalar-Tensor Gravity Models admitting Negative Potentials

TL;DR

This paper explores scalar-tensor gravity models with negative potentials that can produce bouncing universes, demonstrating solutions that pass through a bounce and evolve towards general relativity, even with radiation present.

Contribution

It introduces a class of scalar-tensor models with negative potentials capable of generating bouncing cosmologies with gravity returning to GR after the bounce.

Findings

Viable bouncing solutions exist with negative potentials.

Solutions are robust with nonzero initial radiation.

Gravity approaches GR after the bounce.

Abstract

We consider the possibility to produce a bouncing universe in the framework of scalar-tensor gravity models in which the scalar field potential may be negative, and even unbounded from below. We find a set of viable solutions with nonzero measure in the space of initial conditions passing a bounce, even in the presence of a radiation component, and approaching a constant gravitational coupling afterwards. Hence we have a model with a minimal modification of gravity in order to produce a bounce in the early universe with gravity tending dynamically to general relativity (GR) after the bounce.