Non-locality and late-time cosmic acceleration from an ultraviolet complete theory

TL;DR

This paper proposes a local scalar-tensor gravity model that naturally leads to non-local effects responsible for late-time cosmic acceleration, aligning with observational data and rooted in an ultraviolet complete theory.

Contribution

It introduces a novel local scalar-tensor framework that generates non-local gravity effects, providing a fundamental basis for dark energy phenomena.

Findings

The model fits cosmological data as well as Λ-CDM.

Non-locality emerges from a UV-renormalizable higher-derivative theory.

Residual non-local gravity explains dark energy effects.

Abstract

A local phenomenological model that reduces to a non-local gravitational theory giving dark energy is proposed. The non-local gravity action is known to fit the data as well as $\Lambda$-CDM thereby demanding a more fundamental local treatment. It is seen that the scale-invariant higher-derivative scalar-tensor theory of gravity, which is known to be ultraviolet perturbative renormalizable to all loops and where ghosts become innocuous, generates non-locality at low energies. The local action comprises of two real scalar fields coupled non-minimally with the higher-derivative gravity action. When one of the scalar acquiring the Vacuum Expectation Value (VEV) induces Einstein--Hilbert gravity, generates mass for fields, and gets decoupled from system, it leaves behind a residual theory which in turn leads to a non-local gravity generating dark energy effects.