A density-responsive scalar-field framework for singularity regularization and dynamical dark energy

Abstract

We present a covariant scalar-field framework that unifies the space-time singularity regularization with dynamical dark energy. The theory extends general relativity by introducing a scalar field Φ whose potential couples to the Lorentz-invariant quantity, ensuring manifest covariance. The resulting density-responsive scalar energy exhibits dual behavior: (i) in high-density regimes, it saturates at , providing a Planck-scale upper bound on the total energy density that regularizes classical singularities; (ii) in low-density regimes, it approaches a constant, driving cosmic acceleration as dynamical dark energy. A natural renormalization group evolution with an anomalous dimension γ ≈ 0.501 connects the Planck scale to the meV dark energy scale without fine-tuning. The model makes distinctive, testable predictions and distinguishes it from ΛCDM and standard quintessence models. Despite the novel interaction terms, the fifth forces are suppressed,, ensuring compatibility with all precision gravity tests. This framework demonstrates how a single quantum field theory mechanism can simultaneously address UV singularities and IR dark energy, providing concrete predictions for future Stage-IV cosmological surveys.