We explore the viability of baryogenesis from light scalar decays after theelectroweak phase transition. A minimal model of this kind is constructed withnew CP violating interactions involving a heavy fourth family. The departurefrom thermal equilbrium must come from topological defects like cosmic strings,and we show that almost any mechanism for producing the cosmic strings at theelectroweak scale results in a viable theory. Baryogenesis occurs in the fourthgeneration but the baryon number is later transported to the visiblegenerations. This mechanism of indirect baryogenesis allows us to satisfyexperimental limits on the proton lifetime while still having perturbativebaryon number violation at low energies. The fourth family has very smallmixing angles which opens the possibility of distinct observable signatures incollider experiments.
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