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Title: Isocurvature constraints and anharmonic effects on QCD axion dark matter

We revisit the isocurvature density perturbations induced by quantum fluctuations of the axion field by extending a recently developed analytic method and approximations to a time-dependent scalar potential, which enables us to follow the evolution of the axion until it starts to oscillate. We find that, as the initial misalignment angle approaches the hilltop of the potential, the isocurvature perturbations become significantly enhanced, while the non-Gaussianity parameter increases slowly but surely. As a result, the isocurvature constraint on the inflation scale is tightened as H{sub inf}∼
Authors:
 [1] ; ;  [2]
  1. Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 3H8 (Canada)
  2. Department of Physics, Tohoku University, Sendai 980-8578 (Japan)
Publication Date:
OSTI Identifier:
22282648
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 09; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; AXIONS; DENSITY; ENERGY SPECTRA; FLUCTUATIONS; GEV RANGE; INFLATIONARY UNIVERSE; INFLATONS; LIMITING VALUES; NONLUMINOUS MATTER; PERTURBATION THEORY; POTENTIALS; QUANTUM CHROMODYNAMICS; SCALARS; TIME DEPENDENCE