Attracted to de Sitter: cosmology of the linear Horndeski models

TL;DR

This paper explores specific Horndeski cosmological models capable of dynamically screening vacuum energy, leading to stable de Sitter solutions, and analyzes their properties and realistic implementations.

Contribution

It introduces linear-in-derivative Horndeski models that naturally produce de Sitter vacua and examines their stability and cosmological evolution.

Findings

Models can screen any vacuum energy to produce de Sitter space.

Certain models exhibit attractor behavior ensuring stable cosmic evolution.

Realistic models show promising cosmological dynamics.

Abstract

We consider Horndeski cosmological models, with a minisuperspace Lagrangian linear in the field derivative, that are able to screen any vacuum energy and material content leading to a spatially flat de Sitter vacuum fixed by the theory itself. Furthermore, we investigate particular models with a cosmic evolution independent of the material content and use them to understand the general characteristics of this framework. We also consider more realistic models, which we denote the "term-by-term" and "tripod" models, focusing attention on cases in which the critical point is indeed an attractor solution and the cosmological history is of particular interest.