Resonant production via active–sterile neutrino oscillations in the presence of large lepton asymmetries (the Shi–Fuller mechanism) remains a compelling scenario for keV-scale sterile neutrino dark matter. For a long time, the constraints on such asymmetries were obtained thanks to big bang nucleosynthesis and cosmic microwave background measurements, but did not properly account for the...
The dynamics of neutrinos and antineutrinos at MeV temperatures sets the Standard Model prediction for the effective number of relativistic species, N_{eff}, a key target for upcoming CMB and BBN measurements. Reaching a suitable theoretical accuracy demands control over sub-percent effects in the relevant interaction rates. In this talk I will review recent progress on precision calculations...