We present a geometric derivation of colour confinement, the Yang-Mills mass gap, and the glueball spectrum within the brane-bulk octonionic framework. The central result is that confinement arises from a rank reduction of the 7 × 7 Gram matrix G = −(1 + γ)I7 + γJ7 of the seven imaginary planes of Im(O): when the non-orthogonality parameter γ reaches γconf = 1/Nc (for SU(Nc)), the uniform eigenvalue µ0 = −1 + Ncγ vanishes, the colour- sector metric loses rank, and coloured objects can no longer propagate freely. The glueball is identified as a closed focal zone loop — a self-sustaining standing wave of brane current with no quark endpoints. Its stability rests on two independent mechanisms: (i) topological protection from the discrete Fano geometry — a colour-singlet loop requires all seven Fano nodes to be in phase, and there is no intermediate configuration between a seven-quantum loop and the vacuum; (ii) geometric incompressibility — the brane fluid has auxetic Poisson ratio ν = −1 (Paper IX), making it volume-incompressible so that a closed loop cannot continuously contract to zero. The AdS5 geometry of the bulk (Paper LXII) provides a fifth-dimensional restoring force that enforces this constraint. From these two mechanisms, the glueball mass spectrum is derived with zero free parameters: M(0++) = λ3ΛQCD = 1,519 MeV (lattice: 1,710 MeV, error 11%) and M(2++) = (λ3 + λ2)ΛQCD = 2,387 MeV (lattice: 2,400 MeV, error 0.5%), where λ3 = 7 and λ2 = 4 are the Fano Laplacian eigenvalues (Paper LXII) and ΛQCD = 217 MeV is derived from the G2 boundary condition αG2 = 1/51 (Paper LXII). The framework is not a quantum field theory in the Hilbert space sense: the mass gap is an algebraic theorem about a 7 × 7 real matrix, not a functional-analytic statement about an infinite-dimensional operator algebra. The continuous Yang-Mills field theory is the low-energy effective description of this discrete G2-symmetric geometry. Part of the One-Octonion Brane-Bulk Framework series. Anchor DOI: 10.5281/zenodo.19120873. Community: one-octonion-brane-bulk. Author: Bharathi Dasan Jagadeesan, M.D., University of Minnesota. ORCID: 0000-0002-1143-941X.
Bharathi Jagadeesan (Tue,) studied this question.