  Fermions scattering off first-order phase transition bubbles, in the
framework of $SU(2)_L\otimes SU(2)_R\otimes U(1)$ models, may generate the
Baryon Asymmetry of the Universe (BAU), either at the $LR$-symmetry-breaking
scale, or at the weak scale. In the latter case, the baryon asymmetry of the
Universe is related to CP violation in the $K_0$--$\bar K_0$ system.
