We prove the existence of a positive mass gap Delta = m₁ > 0 in pure SU (N) Yang-Mills theory in four dimensions. The argument proceeds within the SO (3, 3) framework: Yang-Mills theory arises as the four-dimensional projection of the Self-Grounding Equation, a six-dimensional matrix model with signature (3, 3). The three omega-axes (positive signature, e-mode) produce the continuous gauge-field dynamics; the three sigma-axes (negative signature, phi-mode) compactify on the Poincare homology sphere P3 = S3/2I*. On a compact Riemannian manifold, the Laplacian has a discrete spectrum with a strictly positive first eigenvalue. This discreteness is not an approximation but a topological necessity: it follows from the compactness of P3 and the ellipticity of the Laplacian. The mass gap is therefore the phi-mode shadow of the sigma-sector compactification — a constitutive feature of the theory, not a dynamical accident. We show that the denial of the mass gap contradicts the identity between the e-mode description (continuous gauge fields on R4) and the phi-mode description (discrete spectrum from compactification), and is therefore self-refuting.
Gereon Kraemer (Mon,) studied this question.