Real Spectral Exclusion for Singular Chiral Sturm–Liouville Operators

Research Note 11 in the "Geometry of the Critical Line" programme. We prove that a class of singular non-self-adjoint Sturm–Liouville operators with chiral (first-order) coupling admits no real eigenvalues in the Friedrichs form domain. The operator family is H^(m) = −d²/dx² + V_m(x) + imA(x)d/dx + imB(x) on a bounded interval with confining singularities at both endpoints, where m is a nonzero integer parameter. The proof proceeds in three steps: (1) a Frobenius analysis classifies local solutions into a regular branch (|ψ| = O(ε3/2)) and a singular branch (|ψ| = O(ε−1/2)); (2) the Friedrichs form-domain condition (finite kinetic and potential energy) excludes the singular branch; (3) a Wronskian identity, with all boundary terms vanishing for the regular branch, yields 0 = ∫(A′−2B)|ψ|² > 0, a contradiction. The positivity condition A′−2B > 0 holds for any cross-coupling g with g′ > 0. The spectral gap grows linearly with |m|. No perturbation theory is used. The result is applied to the Symmetric Complex Transcendental (SCT) 5-manifold family, where it provides the spectral exclusion theorem used in the conditional Riemann Hypothesis reduction of Paper 40 (DOI: 10.5281/zenodo.19230354).