Relativistic Treatment of Dark Thermalization

Speaker: Takashi Toma

If dark sector is decoupled from the Standard Model sector due to feeble couplings, these two sectors may separately be thermalized with different temperatures. In this case, the Maxwell-Boltzmann distribution is traditionally assumed for dark sector for simplicity regardless of the temperature. In this talk, the full Bose-Einstein distribution is considered in the simplest model of real scalar dark matter. We find that the resultant reaction rates are enhanced compared to the rates with the Maxwell-Boltzmann distribution at high temperature. Our result affects on calculations of relic abundance of dark matter at relativistic regime. We also consider applications of our formalism to the freeze-in mechanism.