DESI and Dynamical Dark Energy from Extended Pre-geometric Gravity

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 $\hat{I}¸$-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 ($\ddot{I}{‡}_{\mathrm{red}}^2=1.394$), deviating from $\hat{I}›\mathrm{CDM}$ by only a few percent in the gravitational slip parameter ${\hat{I}}^3(z)$ with stable tensor perturbations. This analysis establishes a concrete, testable bridge between pre-geometric gravity and cosmic acceleration.

8 pages, 3 figures