  In this conference paper, we consider effective field theories of
non-relativistic dark matter particles interacting with a light force mediator
in the early expanding universe. We present a general framework, where to
account in a systematic way for the relevant processes that may affect the
dynamics during thermal freeze-out. In the temperature regime where
near-threshold effects, most notably the formation of bound states and
Sommerfeld enhancement, have a large impact on the dark matter relic density,
we scrutinize possible contributions from higher excited states and radiative
corrections in the annihilations and decays of dark-matter pairs.
