Abstract
We consider a local phenomenological model to explain a non-local gravity scenario which has been proposed to address dark energy issues. This non-local gravity action has been seen to fit the data as well as $\Lambda$-CDM and therefore demands a more fundamental local treatment. The induced gravity model coupled with higher-derivative gravity is exploited for this proposal, as this perturbatively renormalizable model has a well-defined ultraviolet (UV) description where ghosts are evaded. We consider a generalised version of this model where we consider two coupled scalar fields and their non-minimal coupling with gravity. In this simple model, one of the scalar field acquires a Vacuum Expectation Value (VEV), thereby inducing a mass for one of the scalar fields and generating Newton's constant. The induced mass however is seen to be always above the running energy scale thereby leading to its decoupling. The residual theory after decoupling becomes a platform for driving the accelerated expansion under certain conditions. Integrating out the residual scalar generates a non-local gravity action. The leading term of which is the non-local gravity action used to fit the data of dark energy.
Highlights
Dark energy (DE) has been a puzzling problem which is observed in the Universe in the era of large distance scale where the Universe is seen to be undergoing accelerated expansion [1,2]
We show that integrating out the extra scalar from the residual action results in a nonlocal action whose leading term matches with the nonlocal action considered by [12,13,15]
We tried to understand dark energy and the accelerated expansion it causes at late times of the Universe
Summary
Dark energy (DE) has been a puzzling problem which is observed in the Universe in the era of large distance scale where the Universe is seen to be undergoing accelerated expansion [1,2]. A good and simple way to get an accelerated expansion is by making use of a scalar field where its slow variation with respect to cosmic time give rise to negative pressure. This is the usual scenario in the quintessence model [3,4,5,6,7] and k-essence model [8,9,10]. We aim to address this issue of nonlocality by proposing a local model where such a nonlocality arises naturally when the fields decouple from the system Such decoupling gives the nonlocal action which at late times results in accelerated expansion.
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