Precision study of GeV-scale resonant leptogenesis

Understand

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 &#34;complete&#34; 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 $\Delta M/M \sim 10^{-8}$ as the optimal degeneracy.