On Higgs and sphaleron effects during the leptogenesis era

ENRICO NARDI; YOSEF NIR; J. RACKER; ESTEBAN ROULET

JOURNAL OF HIGH ENERGY PHYSICS - (Online)

IOP PUBLISHING LTD

Año: 2006 vol. 2006 p. 1 - 17

1029-8479

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 > 10^12GeV, 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.