DESI and Dynamical Dark Energy from Extended Pre-geometric Gravity

TL;DR

This paper introduces a quadratic extension of pre-geometric gravity that naturally produces a dynamical dark energy component, fitting observational data well and providing a testable link between fundamental gravity theories and cosmic acceleration.

Contribution

It proposes a novel quadratic pre-geometric gravity model that yields a dynamical dark energy and matches DESI data better than standard models.

Findings

Model fits DESI BAO+FS data with $ ext{chi}^2_{red} = 1.394

Deviates slightly from $ ext{Lambda CDM}$ in gravitational slip parameter

Stable tensor perturbations confirm model viability

Abstract

We consider the simplest quadratic extension of MacDowell-Mansouri pre-geometric gravity preserving the topological pre-volume form symmetry. After symmetry breaking, it becomes $(\mathrm{Lovelock})^2$ gravity, dual to a Galileon-like Horndeski scalar-tensor theory. The gravitational Higgs mechanism forces the Gauss-Bonnet coupling to be inversely proportional to the bare cosmological constant. The quadratic correction renders the gravitational $\theta$-angle dynamical in the form of a gravi-axion, whose effective mass sets the dark energy scale, thus naturally realizing a dynamical dark energy. The model fits DESI's BAO+FS data exceptionally well ($\chi^2_{\rm red} = 1.394$), deviating from $\Lambda\mathrm{CDM}$ by only a few percent in the gravitational slip parameter $\gamma(z)$ with stable tensor perturbations. This analysis establishes a concrete, testable bridge between pre-geometric gravity and cosmic acceleration.