Ultralight Millicharged Dark Matter via Misalignment

Understand

We explore the cosmology and phenomenology of millicharged and millicharge-like dark matter with masses from 1 eV to 10 keV and charges of $10^{-18}$ to $10^{-14}$.

• Dark matter in this mass range cannot be thermally produced, but can arise from non-thermal mechanisms.
• We propose a concrete model employing a spontaneously broken approximate global symmetry, in which millicharged dark matter is produced via the misalignment mechanism.
• We show that this production mechanism is cosmologically consistent and compatible with the observed dark matter abundance.