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. Thus, unlike the axion EDE, there is no need for
elaborate potentials or fine-tuning with respect to the initial condition.
Interestingly, the axion not only produces dark photons, but also explains dark
matter. We find the viable parameter region of the axion decay constant and the
axion mass where dark matter and the H0​ tension can be simultaneously
explained. We also discuss the detectability of the axion in the presence of
axion-photon coupling, and show that the axion can be the QCD axion.Comment: 27 pages, 4 figure