Topological Sources of Gravitational Parity Violation from Eleven Dimensions

We derive a compactification origin for four-dimensional gravitational parity violation in eleven-dimensional supergravity. In the product, block-diagonal limit M11 = M4 × X7, the higher-derivative coupling C3 ∧ X8 contains a mixed component proportional to Tr(R4^2) ∧ Tr(R7^2). For an internal axion mode C3 = θ(x)ω3(y), this sector reduces to a four-dimensional axion-Pontryagin interaction. The physical parity-violating source is the canonically normalized coupling gϑRR = αeff/fθ, where the numerator is an internal curvature pairing and fθ is fixed by the Hodge norm of the same axion mode. A companion C3 ∧ G4 ∧ G4 reduction can generate axion-gauge couplings when suitable smooth or localized gauge sectors are present, yielding a same-axion ratio in which the shared normalization cancels. The result is not a completed baryogenesis model. It is a compactification-to-cosmology interface that relates possible multi-messenger parity observables to a normalized quotient of internal geometric pairings, once sector-specific normalizations and cosmological transfer functions are specified. In this sense, any matter asymmetry produced through this channel would carry a fossil record of the normalized internal geometric source as processed by cosmological evolution, subject to tensor-transfer, anomaly-matching, threshold, and washout constraints.