Accelerating universe as a result of an adjustment mechanism

TL;DR

This paper proposes a scalar-tensor gravity model with a de Sitter vacuum that can dynamically screen vacuum energy, leading to cosmological evolutions consistent with an accelerating universe.

Contribution

It introduces a class of scalar-tensor models with second order equations that maintain a de Sitter critical point regardless of matter content, offering a new approach to cosmic acceleration.

Findings

Models exhibit stable de Sitter solutions for various matter contents

Potential to explain universe's acceleration without fine-tuning vacuum energy

Framework compatible with general scalar-tensor theories

Abstract

In this essay we propose that the theory of gravity's vacuum is described by a de Sitter geometry. Under this assumption we consider an adjustment mechanism able to screen any value of the vacuum energy of the matter fields. We discuss the most general scalar-tensor cosmological models with second order equations of motion that have a fixed de Sitter critical point for any kind of material content. These models give rise to interesting cosmological evolutions that we shall discuss.