WIGNER FUNCTION OF RELATIVISTIC SPIN-1/2 PARTICLES

Using the recently developed relativistic Wigner formulation for the density matrix of spin-1/2 particles, we study the J(pi) = 1/2+ Coulomb-like and cavity relativistic states. One of our objectives is to understand the sharing of the total angular momentum of a quantum state between the spin and rotational degrees of freedom, arising due to the spin-orbit coupling. Another is to demonstrate that the 4 x 4-matrix Wigner function is the appropriate generalization from the 2 x 2 form of the nonrelativistic theory.