The parity-odd TB and EB spectra must vanish in ΛCDM, and they do not: Planck PR4 and WMAP data yield a uniform polarization rotation of beta of about 0.30 to 0.34 degrees at 3.6σ (Eskilt and Komatsu 2022), with the instrument-miscalibration degeneracy broken by Galactic foreground calibration. Taken at face value, the universe rotates polarization, and the standard model contains no sector that can do it.
ΛCDM assumes a statistically parity-even universe: no preferred direction, no handedness, no axial structure anywhere in the initial conditions or the propagation physics. Under that assumption parity-odd correlations are forbidden identically, so any detection forces new physics by construction, and the model has nowhere to put a handedness the sky appears to have.
SCT replaces the hot-dense-center with a superluminal collision, and a collision with nonzero impact parameter hands the observable patch a global axial vector: the inherited angular momentum J = μ(b × v_rel) (P31, P32). An axial vector is precisely a handedness. The mirror image of our patch is a physically different patch, with J reversed, so parity is broken at the level of the initial conditions themselves (P48), not by a new field added to the Lagrangian. A universe born rotating is allowed, indeed expected, to leave parity-odd fingerprints in radiation that has traversed it.
The framework makes the geometry testable: the same J that breaks parity orients the other large-angle anomalies, and SCT requires the CMB dipole to lie perpendicular to the angular-momentum coherence axis (P64). The collision-born handedness therefore predicts that the birefringence signal, the quadrupole-octupole alignment, the hemispherical asymmetry, and the quasar polarization coherence axis are one aligned family, where axion-like explanations leave the rotation angle orientation-free. In epistemic honesty: the qualitative parity violation is premise-grounded, while a quantitative derivation of beta of 0.3 degrees from collision parameters is flagged as outstanding theoretical work, not yet a derived result.
There is no need to invoke an axion-like pseudoscalar with a tuned Chern-Simons coupling; the handedness was deposited with the matter.
The registered kill: a dedicated analysis showing the parity-violation axis and the other anomaly axes (quadrupole-octupole, hemispherical, dipole, quasar polarization) are mutually inconsistent at 3σ breaks the shared-axis prediction that distinguishes collision handedness from field-based birefringence. Independently, LiteBIRD or CMB-S4 tracing the EB signal to foreground modeling or calibration, erasing it, removes the observation; SCT does not require beta at any particular amplitude, but a confirmed isotropic axion-style rotation with no axis correlation would favor the field explanation over geometry.