Pseudoscalar Charge Density of Spin-½ Particles. II. Observability

Abstract

To show clearly that the pseudoscalar charge density is a physical observable, the influence of the pseudoscalar charge density on the spin orientation of a charged spin-\textonehalf{} particle in time-independent electric and magnetic fields is considered. The following results are found: (I). Longitudinal electric field. Because of the interaction of the pseudoscalar charge density with the field, the spin rotates about the axis perpendicular to the direction of propagation and the spin orientation. (II). Transverse electric field. The interaction of the pseudoscalar charge density with the field causes the spin to rotate about the axis perpendicular to the spin and the direction of the field. The interaction of the usual scalar charge density with the field causes the spin to rotate about the axis perpendicular to the direction of propagation and the field. At very low energies, the spin can be rotated through a larger angle in the former case than in the latter. (III). Longitudinal and transverse magnetic fields. There is no interaction between the induced pseudovector current and the magnetic fields.