Ultralight millicharged dark matter via misalignment

A bstract We explore the cosmology and phenomenology of millicharged millicharge-like dark matter with masses from 1 eV to 10 keV charges − 18 14 . Dark in this mass range cannot be thermally produced, but can arise non-thermal mechanisms. propose a concrete model employing spontaneously broken approximate global symmetry, which is produced via misalignment mechanism. show that production mechanism cosmologically consistent compatible observed abundance. This implemented using either fundamental scalars or hidden-sector quarks, coupled Standard Model photon hidden photon. then consider light matter, regardless its cosmological origin, determine parameter space existing experiments observations. significant part new we may accessible near future through direct deflection experiments, measurements cosmic microwave background blackbody spectrum, constraints on plasma instabilities due self-interaction.