  We discuss the effects of various processes that can be active during the
leptogenesis era, and present the Boltzmann equations that take them into
account appropriately. A non-vanishing Higgs number asymmetry is always
present, enhancing the washout of the lepton asymmetry. This is the main new
effect when leptogenesis takes place at $T>10^{12}$ GeV, reducing the final
baryon asymmetry and tightening the leptogenesis bound on the neutrino masses.
If leptogenesis occurs at lower temperatures, electroweak sphalerons partially
transfer the lepton asymmetry to a baryonic one, while Yukawa interactions and
QCD sphalerons partially transfer the asymmetries of the left-handed fields to
the right-handed ones, suppressing the washout processes. Depending on the
specific temperature range in which leptogenesis occurs, the final baryon
asymmetry can be enhanced or suppressed by factors of order 20%--40% with
respect to the case when these effects are altogether ignored.
