  The kinetic decoupling of dark matter (DM) from the primordial plasma sets
the size of the first and smallest dark matter halos. Studies of the DM kinetic
decoupling have hitherto mostly neglected interactions between the DM and the
quarks in the plasma. Here we illustrate their importance using two frameworks:
a version of the Minimal Supersymmetric Standard Model (MSSM) and an effective
field theory with effective DM-quark interaction operators. We connect particle
physics and astrophysics obtaining bounds on the smallest dark matter halo size
from collider data and from direct dark matter search experiments. In the MSSM
framework, adding DM-quark interactions to DM-lepton interactions more than
doubles the smallest dark matter halo mass in a wide range of the
supersymmetric parameter space.
