Experimental tests of curvature couplings of Fermions in General Relativity

Spin 1 2 particles in geodesic trajectories experience no gravitational potential but they still have non-zero couplings to the curvature tensor. The effect of space time curvature on fermions can be parameterized by a vector and a pseudo-vector potential. These apparent CPT violating terms can be measured with satellite based spinpolarized torsion balance and clock comparison experiments. The Earth’s curvature effect is of the order of 10Gev which is not far from the present bounds of ∼ 10Gev on such CPT violating couplings.