2026/07/14 by F.A. Chishtie
paper · doi:10.1139/cjp-2025-0273
crossref issued 2026/07/14 · crossref published 2026/07/14 · crossref published-online 2026/07/14 · crossref created 2026/07/14 · crossref deposited 2026/07/14 · crossref indexed 2026/07/31
The Unified Standard Model with Emergent Gravity (USMEG-EFT) framework achieves Standard Model-gravity unification by treating 4D General Relativity as an effective field theory. This work presents a comparative analysis of Einstein-Cartan (EC) theory and USMEG-EFT against experimental constraints and theoretical consistency requirements, distinguishing minimal EC with algebraically determined torsion from variants in which the spin connection is an independent quantum field. The latter class includes the Faddeev-Popov quantization framework of Brandt, Frenkel, Martins-Filho and McKeon adopted in their unification proposal, and for it gravitational wave polarization measurements directly test the additional propagating degrees of freedom. General relativity's spin-2 graviton produces exactly two tensor polarizations, while EC theory with independent dynamical spin connection predicts up to six modes. LIGO-Virgo-KAGRA null tests for GW170817 favor pure tensor over pure vector and pure scalar hypotheses at Bayes factors exceeding 1020:1, improved to approximately 1026:1 with a gamma-ray-burst jet-orientation prior. Complementary matter-sector constraints from the Standard Model Extension yield |bn_⊥|