2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/206377We explore the possibility that the observed baryon asymmetry of the universe is the result of an earlier phase transition in which an extended gauge sector breaks down into the $SU(3)_C \times SU(2)_L \times U(1)_Y$ of the Standard Model. Our proto-typical example is the Topflavor model, in which there is a separate $SU(2)_1$ for the third generation from the $SU(2)_2$ felt by the first two generations. We show that the breakdown of $SU(2)_1 \times SU(2)_2 \to SU(2)_L$ results in lepton number being asymmetrically distributed through-out the three families, and provided the SM electroweak phase transition is {\em not} strongly first order, results in a non-zero baryon number, which for parameter choices that can be explored at the LHC, may explain the observed baryon asymmetry.25 pages, 6 figures, submitted to PRDHigh Energy Physics - Phenomenologytext