Reflections on the Matter-Dark Matter Coincidence
Dr. Arushi Bodas
Postdoctoral Scholar
Fermilab & EFI, UChicago
The striking similarity between the cosmic abundances of baryons and dark matter, despite their very different astrophysical behavior, strongly motivates the scenario in which dark matter resides within a dark sector that mirrors the structure of the standard model. The coincidence is then explained by an approximate Z_2 exchange symmetry between the two sectors, where the dark matter consists of stable dark neutrons, with matter and dark matter asymmetries arising via parallel WIMP baryogenesis mechanisms. I will present a higher-dimensional realization in the UV, in which the hierarchical couplings of the two sectors and the requisite Z_2-breaking structure arise naturally. I will show how the model can be made compatible with cosmology while maintaining naturalness and emphasise certain potential pitfalls not fully considered in previous literature.