New “dark” fermionic fields charged under a new confining dark gauge group (SU(N) or SO(N)) can come as embeddings in SU(5)−GUT multiplets to explain dark matter (DM).
These fermions would form bound states due to the confining nature of the dark gauge group.
Such dark baryons could prove to be a good neutral DM candidate stable due to a dark baryon
number. The DM relic abundance sets the dark confinement scale to be close to 100 TeV. Previous
works require the mass of these baryonic DM-forming light fields m (with m being lesser than
the dark confinement scale) to be way smaller than the unification scale (GUT scale). This
was done assuming that their GUT partners in SU(5) representations have GUT scale mass. In
our work, focusing on the role of these heavy GUT states in these models, we find that the dark
fermions cannot come in almost degenerate GUT multiplets. We further find that cosmological
constraints from Big Bang Nucleosynthesis in addition to unification requirements allow for only
certain values of masses for these GUT fermions. However, these mass values give a too large
contribution to the DM relic abundance. To evade this, the mass of the GUT states must be lower
than the reheating temperature.