QCD Axion Dark Matter from a Late Time Phase Transition

Understand

We investigate the possibility that the Peccei-Quinn phase transition occurs at a temperature far below the symmetry breaking scale.

• Low phase transition temperatures are typical in supersymmetric theories, where symmetry breaking fields have small masses.
• We find that QCD axions are abundantly produced just after the phase transition.
• The observed dark matter abundance is reproduced even if the decay constant is much lower than $10^{11}$ GeV.