Cosmological and astrophysical probes of dark baryons

Understand

We examine the cosmological and astrophysical signatures of a "dark baryon," a neutral fermion that mixes with the neutron.

• As the mixing is through a higher-dimensional operator at the quark level, production of the dark baryon at high energies is enhanced so that its abundance in the early universe may be significant.
• Treating its initial abundance as a free parameter, we derive new, powerful limits on the properties of the dark baryon.
• Primordial nucleosynthesis and the cosmic microwave background provide strong constraints due to the inter-conversion of neutrons to dark baryons through their induced transition dipole, and due to late decays of the dark baryon.