A unified geometric description of the Universe: from inflation to late-time acceleration without an inflaton nor a cosmological constant

TL;DR

This paper introduces a gravitational model with higher-order curvature invariants that explains the universe's entire evolution, from inflation to late-time acceleration, without needing an inflaton or cosmological constant, suggesting dark energy is purely geometric.

Contribution

The model provides a unified geometric framework for cosmic evolution, eliminating the need for dark energy or inflaton fields, and reproduces observed acceleration with second-order field equations.

Findings

Reproduces inflation and late-time acceleration without additional fields.

Consistent with observed cosmic acceleration at low redshift.

Reinterprets dark energy as a geometric effect.

Abstract

We present a cosmological model arising from a gravitational theory with an infinite tower of higher-order curvature invariants that can reproduce the entire evolution of the Universe: from inflation to late-time acceleration, without invoking an inflaton nor a cosmological constant. The theory is Einsteinian-like. The field equations for a Friedmann-Lema\^{i}tre-Robertson-Walker metric are of second-order and can reproduce a late-time evolution that is consistent with the acceleration provided by the cosmological constant at low redshift. Our results force us to reinterpret the nature of dark energy, becoming a mechanism that is inherited solely from the geometry of spacetime.