Baryogenesis and damping in nonminimal electroweak models

We study the effect of damping on the generation of baryon asymmetry of the Universe in the standard model of the eletroweak theory with simple extensions of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are considered, taking into account their markedly different dispersion relations due to interaction with the hot electroweak plasma. It is argued that the contribution of the b quark can be comparable to that of the t quark calculated earlier.