Altered Axion Abundance from a Dynamical Peccei-Quinn Scale
  We build a model in which the relic abundance of axions is altered from the
standard misalignment mechanism, either increased or decreased, due to the
presence of a new light scalar that couples to the radial part of the
Peccei-Quinn (PQ) field. The light scalar makes the effective PQ
symmetry-breaking scale dynamical, altering the early-time dynamics for the
axion and affecting its late-time dark matter abundance. We analyze this new
mechanism semi-analytically and numerically, showing that we can accommodate
both lighter or heavier axion dark matter, compared to the standard treatments.
We discuss implications of the model for axion searches and fundamental
physics.
