Abstract
We show how thermal leptogenesis induced by the CP-violating decay of a right-handed neutrino (RHN) can be compatible to the assumption of quintessential kination, i.e., to a cosmological background model where the energy density of the early Universe is assumed to be dominated by the kinetic term of a quintessence field during some epoch of its evolution. The phenomenology depends on the temperature Tr above which kination dominates over radiation. We show that for some choice of Tr not far from the RHN mass M, M/100 < Tr < M, the efficiency for leptogenesis can be even larger than in the standard scenario of radiation domination. On the other hand, when Tr ≪ M a super-weak wash-out regime is attained, with a strong suppression of the efficiency. In this case successful leptogenesis depends sensitively on ΔL = 1 scattering processes and requires a resonant CP violation effect of order unity. Moreover, the condition Tr > 5 MeV (M/TeV) (0.05 eV/m) must be verified, with m the effective neutrino mass scale.
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