Neutrino Escape and Marginal Trapping in Q-Interaction Collapse

Paper V of the Early Black-Hole Formation Series examines how neutrino escape through a finite core surface can affect marginal trapping in the dense collapse benchmark of Paper IV. It reproduces eight reference runs and evolves collisionless neutrino transport on the prescribed closed FLRW background. For the reference shell at χ = π/4, the marginal event occurs before an inward null signal from the surface at χ_b = 5π/12 can arrive. With matched interior data and causal evolution, the 24.464 ms advance due to nuclear feedback is preserved under changes confined to the surface or exterior. By that event, 14.879% of the conformally rescaled emitted energy has crossed the transparent surface. At the outer shell χ = 0.95, the transparent solution gives a neutrino energy density 1.62% below the reflecting control at the marginal event on the fixed matter and geometry background. The reproduction materials document the LaTeX build, transport solver, convergence checks, and independent flux calculation.