An Effective Dark-Energy Sector from Domain-Wall Parametric Resonance

This work proposes an effective mechanism by which a dark-energy-like expansion rate can emerge from parametric resonance in a non-equilibrium boundary layer of a field-theoretic system, rather than being inserted directly as a fundamental cosmological constant. A scalar collective mode localized on a domain wall between two competing phases is governed, after two explicit assumptions, by an effective equation of motion whose frequency becomes time-dependent through the interplay between continuous renormalization-group flow and discrete sectoral mixing. This promotes the originally forced oscillator into a Hill/Mathieu-type parametric oscillator with a dynamically modulated effective mass. The resulting envelope growth defines a positive emergent expansion rate H eff. Numerical analysis shows that Heff depends non-monotonically on the discrete sectoral parameter, develops resonance peaks, and collapses in the symmetric limit where the competing flow directions coincide. These features support the interpretation that the observed dark-energy scale could, in such a framework, correspond not to the bare vacuum density itself, but to a residual effective expansion rate after domain-wall resonance and FRG coarse-graining. A quantitative explanation of the observed cosmological hierarchy, however, remains open and requires a continuous deformation parameter together with a Floquet analysis demonstrating genuine exponential suppression