  We study the formation of Dark Matter nuclei in scenarios where DM particles
are baryons of a new confining gauge force. The dark nucleosynthesis is
analogous to the formation of light elements in the SM and requires as a first
step the formation of dark deuterium. We compute this process from first
principles, using the formalism of pion-less effective theory for
nucleon-nucleon interactions. This controlled effective field theory expansion
allows us to systematically compute the cross sections for generic SM
representations under the assumption of shallow bound states. In the context of
vector-like confinement models we find that, for nucleon masses in the TeV
range, baryonic DM made of electro-weak constituents can form a significant
fraction of dark deuterium and a much smaller fraction of dark tritium.
Formation of dark nuclei can also lead to monochromatic photon lines in
indirect detection. Models with singlets do not undergo nucleosynthesis unless
a dark photon is added to the theory.
