Magnetic moments and general covariance

The principle of general covariance for deriving the passive equations is applied to the group of automorphisms of compact support of a principal bundle acting on the space of Cartan connections. Under an orbital constraint this yields the equations of motion postulated in [11] which have a symplectic character. When specialized to an affine connection these equations become the equations of interaction of spin and torsion studied in [5]. With the incorporation of a Higgs field, a forcing term is added to the equations which, in the case of an electromagnetic field, incorporate the effects of the magnetic moment. The Higgs field is of the character obtained by dimensional reduction.