IV.T149 — Lepton σ-Matrix Exponents from PDG Back-Solve

Back-solving M_ℓ=[[a,b,0],[b,c,b],[0,b,a]] from PDG masses (m_e=0.511, m_μ=105.658, m_τ=1776.86 MeV) with a=m_μ (σ-odd eigenvalue): a=105.658 MeV, c=m_e+m_τ−m_μ=1671.713 MeV, b=√((m_μ·c−m_e·m_τ)/2)=296.414 MeV. In ι_τ-units relative to m_n=939.565 MeV: p_l=log(a/m_n)/log(ι_τ)=2.033, q_l=log(b/m_n)/log(ι_τ)=1.073, r_l=log(c/m_n)/log(ι_τ)=−0.536. Eigenvalue verification: exact match (residual <10⁻⁴⁸ MeV). Comparison with neutrino exponents (p_ν=3.7, q_ν=4.8, r_ν=2.8): lepton exponents are systematically lower by ~3.3 units, reflecting B-sector (EM) vs A-sector (Weak) coupling difference.