Baryogenesis from a Primordial Lepton Asymmetry
  We examine the generation of baryon asymmetry at the weak scale from a primordial lepton asymmetry. If the electroweak phase transition is first order, partial reflection of tau leptons off the bubble walls and the resulting hypercharge transport into the symmetric phase, gives rise to a baryon number consistent with observation. 
S.A.Abel and K.E.C.Benson