  In a companion paper (to be presented), lattice field theory methods are used
to show that in two-color, two-flavor QCD there are stable nuclear states in
the spectrum. As a commonly studied theory of composite dark matter, this
motivates the consideration of possible nuclear physics in this and other
composite dark sectors. In this work, early Universe cosmology and indirect
detection signatures are explored for both symmetric and asymmetric dark
matter, highlighting the unique features that arise from considerations of dark
nuclei and associated dark nuclear processes. The present day dark matter
abundance may be composed of dark nucleons and/or dark nuclei, where the latter
are generated through it dark nucleosynthesis. For symmetric dark matter,
indirect detection signatures are possible from annihilation, dark
nucleosynthesis, and dark nuclear capture and we present a novel explanation of
the galactic center gamma ray excess based on the latter. For asymmetric dark
matter, dark nucleosynthesis may alter the capture of dark matter in stars,
allowing for captured particles to be processed into nuclei and ejected from
the star through dark nucleosynthesis in the core. Notably, dark
nucleosynthesis realizes a novel mechanism for indirect detection signals of
asymmetric dark matter from regions such as the galactic center, without having
to rely on a symmetric dark matter component.
