Leptogenesis from first principles in the resonant regime

Abstract

The lepton asymmetry generated by the out-of-equilibrium decays of heavy Majorana neutrinos with a quasi-degenerate mass spectrum is resonantly enhanced. In this work, we study this scenario within a first-principle approach. The quantum field theoretical treatment is applicable for mass splittings of the order of the width of the Majorana neutrinos, for which the enhancement is maximally large. The non-equilibrium evolution of the mixing Majorana neutrino fields is described by a formal analytical solution of the Kadanoff–Baym equations, that is obtained by neglecting the back-reaction. Based on this solution, we derive approximate analytical expressions for the generated asymmetry and compare them to the Boltzmann result. We find that the resonant enhancement obtained from the Kadanoff–Baym approach is smaller compared to the Boltzmann approach, due to additional contributions that describe coherent transitions between the Majorana neutrino species. We also discuss corrections to the masses and widths of the degenerate pair of Majorana neutrinos that are relevant for very small mass splitting, and compare the approximate analytical result for the lepton asymmetry with numerical result

NonthermalCPviolation in soft leptogenesis

“…[49] which gives the dependence on the distribution functions 1+η i f eq i +η j f eq j in agreement with the results derived from nonequilibrium quantum field theory [48,[50][51][52][53][54][55][56][57][58][59][60][61][62] in contrast to the results of Refs. [31,63] …”

Axion models with high scale inflation

“…by the Affleck-Dine mechanism [67,68], survives the dilution due to thermal inflation and it explains the present baryon asymmetry of the universe. Note also that the temperature after thermal inflation increases to T max ∼ 10 7−8 GeV, and hence it is also possible that thermal leptogenesis [69] works if there is a mild degeneracy among right-handed neutrino masses [70][71][72][73].…”

Toward a Nonequilibrium Green Functions Approach to Diffusion in Strongly Coupled Finite Quantum Systems

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