Relativistic classical limit of quantum theory.

Abstract

We study the classical limit of the equal-time relativistic quantum transport theory. We discuss in qualitative terms the need to fold first the Wigner function with a coarse-graining function. Only then does the singularity at \ensuremath{\Elzxh}\ensuremath{\rightarrow}0 seem to be manageable. In the limit \ensuremath{\Elzxh}\ensuremath{\rightarrow}0, we obtain the relativistic Vlasov equations for the particle and the antiparticle sector of the Fock space. Similarly, we address the evolution equations of the spin and the magnetic-moment density.