Fab 5: Noncanonical Kinetic Gravity, Self Tuning, and Cosmic Acceleration

TL;DR

This paper explores a nonlinear kinetic gravity model that enables cosmic acceleration and self-tuning of the cosmological constant without introducing extra degrees of freedom, offering new insights into gravity's behavior.

Contribution

It introduces a nonlinear combination of kinetic gravity terms that achieves acceleration and self-tuning within scalar-tensor theories, expanding the understanding of gravity models.

Findings

Achieves cosmic acceleration without extra degrees of freedom

Demonstrates self-tuning of a large cosmological constant

Provides new properties for exploring gravity behaviors

Abstract

We investigate circumstances under which one can generalize Horndeski's most general scalar-tensor theory of gravity. Specifically we demonstrate that a nonlinear combination of purely kinetic gravity terms can give rise to an accelerating universe without the addition of extra propagating degrees of freedom on cosmological backgrounds, and exhibit self tuning to bring a large cosmological constant under control. This nonlinear approach leads to new properties that may be instructive for exploring the behaviors of gravity.