Two-beam Multiparticle Many-body Inhomogeneous FFI: an extended study

Neutrino flavor evolution in dense astrophysical environments is inherently nonlinear and sensitive to many-body (MB) quantum effects beyond the mean-field (MF) approximation. Existing MB studies are constrained by small system sizes, closed boundaries, and highly idealized symmetry assumptions. We present a unified tensor-network framework that enables reliable simulations of two-beam, multiparticle, inhomogeneous flavor evolution under conditions relevant to core-collapse supernovae and neutron-star mergers. Within this framework, we systematically examine the effects of homogeneities, asymmetricity in flavor states, boundaries, spatial configurations, and fixed-density scaling, allowing direct comparison of these setups under one consistent formulation. Open boundary conditions eliminate artificial correlations while spatial geometry and fixed-density scaling reveal distinct coherence and equilibration behaviors. Our work extends the scope of existing MB literature, providing a physically grounded and computationally robust foundation for modeling effects like FFI in quantum kinetic theory under realistic, inhomogeneous neutrino systems.