From de Sitter to Radiation Dominance: A Dynamical Solution to the Vacuum Energy Problem

Abstract
The enormous discrepancy between theoretical estimates of vacuum energy and cosmological observations remains a fundamental challenge. We propose a model of dynamical vacuum energy compensation based on a scalar field $\phi$ non-minimally coupled to the curvature scalar $R$ through an interaction  $\beta R \phi^2 f(\phi)$. Our results demonstrate that an initial exponential expansion, driven by a large cosmological constant, naturally relaxes into a power-law regime. We show, both analytically and numerically, that this mechanism effectively "neutralizes" the vacuum energy, leading to a realistic cosmology dominated by relativistic matter with $H \approx 1/(2t)$.
 

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