Generalized Uhlenbeck-Goudsmit hypothesis

In this paper the connection between the dipole moment tensorD and the spin four-tensor S is formulated in the form of the generalized Uhlenbeck-Goudsmit hypothesis, D = gSS . It is also found that the spin four-tensor S can be decomposed into two 4-vectors, the usual “space-space” intrinsic angular momentum S and a new one, the “time-space” intrinsic angular momentum Z, which are both equally well physical quantities. Taking into account the generalized Uhlenbeck-Goudsmit hypothesis, the decomposition of S and the decomposition of D into the dipole moments m and d we find that an electric dipole moment (EDM) of a fundamental particle, as a four-dimensional geometric quantity, is determined by Z and not, as generally accepted, by the spin S. Also it is proved that neither the T inversion nor the P inversion are good symmetries in the 4D spacetime. In our geometric approach only the world parity W , x → −x, is well-defined in the 4D spacetime. The consequences for elementary particle theories and experiments that search for EDM are briefly discussed.