V.D245 — SA-i mod-5 Formal Proof: Geometric Series Mechanism

SA-i mod-5 formal proof: the 5 generators {α,π,γ,η,ω} act cyclically (ℤ/5ℤ) on τ³ via σ-involution. Each contributes ι_τ³ = ι_τ^{dim(τ³)}. Geometric series S₅ = Σ_{k=0}^4 ι_τ^{3k} = (1−ι_τ^15)/(1−ι_τ³) = 1.04140. Suppression factor ι_τ^15 with 15 = 3×W₃(4) = dim(τ³)×|generators|. Parallel to Strong CP (SA-i mod-3 → ι_τ^9 → θ_QCD=0, IV.T160).