Conceptos básicos acerca del espín, helicidad, quiralidad y polarización de una partícula de Dirac

The recent technological advances, based on the profound understanding of the electrońs inherent characteristics are the elements that are ready to innovate the technology of information, as well as to refine the (MRI) technique of imagery through the efect of magnetic resonance, which is crucial as a tool for diagnosis and generation of views of live tissues without invasion or harm. So, with the intention to explain the basic theoretical concepts, which are, in general, not clarified in the specialized literature and traditional textbooks, which are related with the particles in Dirac equation, we analize the quantum operators that project some of their peculiar characteristics. These operators are related with the conserved quantities in the theory and therefore with the symmetries of the system. We consider the Hamiltonian formulation to establish the conservation principle and the properties of the projectors that determine the helicity, quirality and polarization of the Dirac particles.