Isocurvature forecast in the anthropic axion window
- LAPTh, Université de Savoie, CNRS, BP 110, F-74941 Annecy-le-Vieux Cedex (France)
- Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)
- Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, D-80805 München (Germany)
- Theory Division, Physics Department, CERN, CH-1211 Genève 23 (Switzerland)
We explore the cosmological sensitivity to the amplitude of isocurvature fluctuations that would be caused by axions in the ''anthropic window'' where the axion decay constant f{sub a} >> 10{sup 12} GeV and the initial misalignment angle Θ{sub i} << 1. In a minimal ΛCDM cosmology extended with subdominant scale-invariant isocurvature fluctuations, existing data constrain the isocurvature fraction to α < 0.09 at 95% C.L. If no signal shows up, Planck can improve this constraint to 0.042 while an ultimate CMB probe limited only by cosmic variance in both temperature and E-polarisation can reach 0.017, about a factor of five better than the current limit. In the parameter space of f{sub a} and H{sub I} (Hubble parameter during inflation) we identify a small region where axion detection remains within the reach of realistic cosmological probes.
- OSTI ID:
- 22273152
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2009, Issue 06; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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