Early Dark Energy and Dark Photon Dark Matter from Waterfall Symmetry Breaking

Understand

We investigate a cosmological model wherein a waterfall symmetry breaking occurs during the radiation-dominated era.

• The model comprises a complex waterfall field, an axion field, and the gauge field (dark photon) generated through a tachyonic instability due to the Chern-Simons interaction.
• Prior to symmetry breaking, the total energy density incorporates a vacuum energy from the waterfall field, establishing a novel scenario for Early Dark Energy (EDE).
• Subsequent to the symmetry breaking, the dark photon dynamically acquires mass via the Higgs mechanism, potentially contributing to the dark matter abundance.