Zero-Sum Multi-Sector Cosmology: A Gravitational Framework for Dark Matter, Baryogenesis, and Cosmic Structure

We present a cosmological framework in which the Universe consists of N co‑located sectors interacting only through gravity. The total baryon number vanishes as a zero‑sum constraint, partitioned across sectors at a primordial sectorization transition parameterized by a symmetry‑breaking potential and a CP‑violating chemical potential. This purely gravitational construction provides unified explanations for dark matter, baryogenesis, galactic rotation curves, the cusp–core problem, early black hole growth, and superluminous supernova energetics. The paper includes analytic derivations and MCMC rotation‑curve fits to SPARC galaxies that support the geometric core prediction. The framework makes sharp, falsifiable predictions: spatially correlated Einstein‑ring mass excesses, S‑star orbital residuals, a calculable ΔNeff signal, and a multi‑peaked stochastic gravitational‑wave background.