Dark Matter Freeze-out and Freeze-in beyond Kinetic Equilibrium

  • Andrzej Hryczuk National Centre for Nuclear Research
Keywords: Dark matter


In the standard approach to the determination of the dark matter (DM) thermal relic abundance, both
from thermal freeze-out and freeze-in mechanisms, one takes into account only the zeroth moment of the
Boltzmann equation, i.e., the equation for the evolution of the particle number density. In case of freezeout,
this comes from the assumption of local thermal equilibrium, while for freeze-in, this comes from
neglecting DM annihilation processes. This proceedings report discusses how to go beyond this assumption,
reports on the introduction of DRAKE—a numerical precision tool that can trace not only the dark
matter relic density but also its velocity dispersion and full phase space distribution function—and finally
presents a new mechanism of decreasing the dark matter relic density through injecting even more DM
particles into the thermal bath.

Special Issue on Neutrinos and Dark Matter-2022