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arXiv · 1811.01971

Precision study of GeV-scale resonant leptogenesis

J. Ghiglieri·M. Laine
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Abstract

Low-scale leptogenesis is most efficient in the limit of an extreme mass degeneracy of right-handed neutrino flavours. Two variants of this situation are of particular interest: large neutrino Yukawa couplings, which boost the prospects of experimental scrutiny, and small ones, which may lead to large lepton asymmetries surviving down to T < 5 GeV. We study benchmarks of these cases within a "complete" framework which tracks both helicity states of right-handed neutrinos as well as their kinetic non-equilibrium, and includes a number of effects not accounted for previously. For two right-handed flavours with GeV-scale masses, Yukawa couplings up to $|h| \sim 0.7 \times 10^{-5}$ are found to be viable for baryogenesis, with $ΔM/M \sim 10^{-8}$ as the optimal degeneracy. Late-time lepton asymmetries are most favourably produced with $ΔM/M \sim 10^{-11}$. We show that the system reaches a stationary state at T < 15 GeV, in which lepton asymmetries can be more than $10^3$ times larger than the baryon asymmetry, reach flavour equilibrium, and balance against helicity asymmetries.

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J. Ghiglieri, M. Laine. 2019-02-08. Precision study of GeV-scale resonant leptogenesis. https://doi.org/10.1007/jhep02(2019)014

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