Magnetic and gravitational moments of higher spin particles

Consistent equations for spin-S particles in an electromagnetic field discovered recently by Buchdahl (J. Phys. A.; 15:1(1982)) are shown in a non-relativistic approximation to describe particles with a gyromagnetic ratio equal to the reciprocal of the spin. The corresponding equations for a particle in a Riemann space are derived and the field-intrinsic spin interaction discussed. It is shown how the equations may be modified, without altering their consistency, to give the particles arbitrary gyromagnetic and 'gyrogravitational' ratios. Finally, in the gravitational case, it is shown that the equations have the most simple behaviour under conformal transformations when the ratio is the reciprocal of the spin. However, conformal invariance only obtains for spin-zero particles and for massless spin-1/2 and spin-1 particles, in which cases one has the usual equations. (author)