Axions, inflation and the anthropic principle

作者：Mack Katherine J^*

来源：Journal of Cosmology and Astroparticle Physics, 2011, (7): 021.

DOI：10.1088/1475-7516/2011/07/021

• axions
• string theory and cosmology
• physics of the early universe

The QCD axion is the leading solution to the strong-CP problem, a dark matter candidate, and a possible result of string theory compactifications. However, for axions produced before inflation, symmetry-breaking scales of f(a) greater than or similar to 10(12) GeV (which are favored in string-theoretic axion models) are ruled out by cosmological constraints unless both the axion misalignment angle theta(0) and the inflationary Hubble scale H-I are extremely fine-tuned. We show that attempting to accommodate a high-f(a) axion in inflationary cosmology leads to a fine-tuning problem that is worse than the strong-CP problem the axion was originally invented to solve. We also show that this problem remains unresolved by anthropic selection arguments commonly applied to the high-f(a) axion scenario.

• 出版日期2011-7