Z4DP II: Sector-Dependent Dynamics of an Elastic Superfluid Vacuum

This document presents Z4DP II as a continuation of the original Z4DP framework, in which the physical vacuum is modeled as a relativistic elastic superfluid. While Z4DP I established the theoretical foundations with an emergent acoustic metric and elastic response, Z4DP II extends the model by introducing sector-dependent dynamics that allow for a consistent description of different types of interactions (massive particles, phonons, light). This resolves potential conflicts with observations, such as the secular perihelion precession of planetary orbits (reproduced with accuracy exceeding 99%) and optical tests (requiring $\gamma\approx1$). The model is validated through numerical simulations in REBOUND and offers prospects for cosmological applications. The work demonstrates a clear progression from kinematic agreement to dynamical prediction, without assuming geometric curvature as a fundamental principle.