Making the Universe at 20 MeV

Understand

We present a testable mechanism of low-scale baryogenesis and dark matter production in which neither baryon nor lepton number are violated.

• Charged $D$ mesons are produced out-of-equilibrium at tens of MeV temperatures.
• The $D$ mesons quickly undergo CP-violating decays to charged pions, which then decay into dark-sector leptons without violating lepton number.
• To transfer this lepton asymmetry to the baryon asymmetry, the dark leptons scatter on additional dark-sector states charged under lepton and baryon number.