http://arxiv.org/abs/1403.4186
The BICEP2 experiment announced the discovery of the primordial B-mode polarization, which determines the Hubble parameter during inflation to be about $10^{14}$GeV. Such high inflation scale is in tension with the QCD axion dark matter if the Peccei-Quinn symmetry remains broken during and after inflation, because too large axion isocurvature perturbations would be generated. The axion isocurvature perturbations can be suppressed if the axion acquires a sufficiently heavy mass during inflation. We show that this is realized if the Peccei-Quinn symmetry is explicitly broken down to a discrete symmetry and if the breaking is enhanced during inflation. Such enhancement is possible if during inflation the saxion acquires a vacuum expectation value much larger than in the present vacuum, or if the symmetry breaking operators depend on the inflaton field value. The latter possibility can be implemented easily in a large-field inflation model.
T. Higaki, K. Jeong and F. Takahashi
Tue, 18 Mar 14
10/62