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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2601.01938 |
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Table of Contents:
- The statistical tension between early and late universe measurements of the Hubble constant ($H_0$) suggests that the dark sector is dynamical rather than static. We propose that this dynamics arises from a fundamental symmetry principle: the Spontaneous Breaking of Scale Invariance. We introduce the Dilaton ($χ$), a Pseudo-Nambu-Goldstone Boson (PNGB) associated with dilatation symmetry breaking. We demonstrate that a simple quadratic mass term in the fundamental theory transforms, via conformal coupling to gravity, into a ''thawing'' exponential potential $V(ϕ) \propto e^{-λϕ}$ in the Einstein frame. Using recent Bayesian reconstructions of dark energy dynamics from Planck, Pantheon+, and SH0ES data, we constrain the potential slope to be $λ\approx 0.056$. We show that this observational value is not arbitrary but corresponds to a fundamental non-minimal coupling strength of $ξ\approx 7.8 \times 10^{-4}$. The Dilaton mechanism naturally generates the late-time equation of state evolution ($w_0 \approx -0.85$) required to alleviate the Hubble tension while protecting the field mass $m \sim H_0$ through approximate shift symmetry.