RELATIVISTIC KINETIC-EQUATIONS FOR ELECTROMAGNETIC, SCALAR, AND PSEUDOSCALAR INTERACTIONS - REMARKS

It is found that the extra quantum constraints to the spinor component s of the equal-time Wigner function given in a recent paper by Zhuang and Heinz should vanish identically. We point out here the origin of t he error and give an interpretation of the result. However, the princi pal idea of obtaining a complete equal-time transport theory by energy averaging the covariant theory remains valid. The classical transport equation for the spin density is also found to be incorrect. We give here the correct form of that equation and discuss briefly its structu re.