  We study the possibility that dark matter re-enters kinetic equilibrium with
a radiation bath after kinetic decoupling, a scenario we dub kinetic
recoupling. This naturally occurs, for instance, with certain types of
resonantly-enhanced interactions, or as the result of a phase transition. While
late kinetic decoupling damps structure on small scales below a cutoff, kinetic
recoupling produces more complex changes in the power spectrum that depend on
the nature and extent of the recoupling period. We explore the features that
kinetic recoupling imprints upon the matter power spectrum, and discuss how
such features can be traced to dark matter microphysics with future
observations.
