The Canonical Quarter-Threshold Dirac Operator Is the Carrier, Not the Zero Operator
The Fourier-exchanged factors and form the self-adjoint two-sector Dirac operator
Its square has the common diagonal block
The theta frontier current is
Thus the quarter-threshold operator is source-derived. But its spectrum is the continuous interval , not the discrete Riemann-zero measure.
It is the canonical archimedean carrier. The integer comb must still supply an arithmetic boundary condition, extension, or scattering determinant that selects discrete resonance data.
Research artifact: research/grothendieck/the-canonical-quarter-threshold-dirac-operator-is-the-carrier-not-the-zero-operator.md