Theoretical and experimental basis for excluding Einstein-Cartan theory within the USMEG-EFT framework

Abstract

The USMEG-EFT framework~\cite{ChishtieEFT2025,ChishtieBreakdown2023} provides systematic quantum gravity through with 4D General Relativity (GR) achieving Standard Model-gravity unification. This work examines Einstein-Cartan theory against McKeon et al.'s claims~\cite{BrandtFrenkelMcKeon2024,McKeonBrandtFrenkel2025} regarding its viability for unification. McKeon et al.'s 2024 analysis omitted key interaction terms, missing Einstein-Cartan's central content. Their 2025 claim that unification requires Einstein-Cartan is incorrect. When fermions are included, Einstein-Cartan generates non-renormalizable four-fermion interactions producing catastrophic quartic divergences $\sim \kappa^4\Lambda^4$. Precision experiments exclude the theory: MICROSCOPE constrains equivalence principle violations at $10^{-15}$ while Einstein-Cartan predicts $10^{-12}$ effects. In contrast to these claims, the USMEG-EFT framework achieves unification using standard 4D GR through constraints, producing finite results with calculable coefficients while remaining experimentally compatible.