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

In a geometric approach to special relativity 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 also 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 $% \mathbf{S}$. The consequences for elementary particle theories and experiments that search for EDM, and also for the investigation of quantum phase shifts with dipoles, are briefly discussed