The Intrinsic Electric Dipole Moment and the "Time-Space" Intrinsic Angular Momentum

In this paper it is found that the spin four-tensor $S^{ab}$ can be decomposed into two 4-vectors, the usual ``space-space'' intrinsic angular momentum $S^{a}$ and a new one, the ``time-space'' intrinsic angular momentum $Z^{a}$, which are both equally well physical quantities. It is shown that an electric dipole moment (EDM) of a fundamental particle, as a four-dimensional geometric quantity, is determined by $Z^{a}$ and not, as generally accepted, by the spin $\mathbf{S}$. 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 $W$, $$, is well-defined in the 4D spacetime. The consequences for elementary particle theories and experiments that search for EDM are briefly discussed.