IV.R419 — Jarlskog Invariant from Wolfenstein at −8750 ppm

J = A²λ⁶η̄ = 3.05×10⁻⁵ at −8750 ppm from PDG 3.08×10⁻⁵. Limited by η̄; improving η̄ to sub-1000 ppm would give sub-percent J.