http://arxiv.org/abs/1703.08798
We show that axion-like particles constituting 100% of the cold dark matter observed and of mass below a certain value $\bar{m}$ must have originated during the inflationary period only, populating the so-called “anthropic window” of the axion parameter space. The numerical value of $\bar{m}$ ranges between 10neV and 0.5peV, depending on the value of the ALP susceptibility. The bound on the ALP mass comes from the non-observation of primordial gravitational waves, which constrains the energy scale of inflation thus the energy scale of the axion-like particle. We also show that, in the anthropic window, the constraint on the energy scale of inflation is orders of magnitude smaller than what derived from the non-observation of primordial gravitational waves, the exact value depending on the ALP mass.
L. Visinelli
Tue, 28 Mar 17
38/68
Comments: 6 pages, 2 figures