Early dark energy by dark Higgs, and axion-induced non-thermal trapping

Understand

We propose a new scenario of early dark energy (EDE) with a dark Higgs trapped at the origin.

• To keep this dark Higgs trapped until around the matter-radiation equality, we use dark photons produced non-thermally by coherent oscillations of axions, which have a much stronger trapping effect than thermal mass.
• When the trapping ends, the dark Higgs quickly decays into dark photons, which are then red-shifted as radiation.
• The dark Higgs EDE scenario works well for an ordinary Mexican-hat potential, and the dark Higgs naturally sits at the origin from the beginning, since it is the symmetry-enhanced point.