Dirac Theory in Hydrodynamic Form

We consider quantum mechanics written in hydrodynamic formulation for the case of relativistic spinor fields to study their velocity: within such a it is possible see that velocity as usually defined can not actually represent tangent vector trajectories particles. propose an alternative definition this and hence particles, which we believe be new only one possible. discuss how these results are necessary step take order face further problems, like multi-particle systems or ensembles, they happen useful many applications interpretations mechanics.