IV.T154 — GIM-Analog Cancelation from σ-Equivariance

σ-equivariance forces uniform off-diagonal element b = ι_τ^q in all three generation rows/columns of the mass matrix, giving Σ_gen b² = 3ι_τ^{2q} = constant. This automatic uniformity suppresses flavour-changing neutral currents (FCNC) analogously to the GIM mechanism.