Breakdown of semiclassical methods in de Sitter space
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W, Hamilton, Ontario (Canada)
- Department of Physics, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213 (United States)
Massless interacting scalar fields in de Sitter space have long been known to experience large fluctuations over length scales larger than Hubble distances. A similar situation arises in condensed matter physics in the vicinity of a critical point, and in this better-understood situation these large fluctuations indicate the failure in this regime of mean-field methods. We argue that for non-Goldstone scalars in de Sitter space, these fluctuations can also be interpreted as signaling the complete breakdown of the semi-classical methods widely used throughout cosmology. By power-counting the infrared properties of Feynman graphs in de Sitter space we find that for a massive scalar interacting through a λ φ{sup 4} interaction, control over the loop approximation is lost for masses smaller than m ≅ √λ H/2π, where H is the Hubble scale. We briefly discuss some potential implications for inflationary cosmology.
- OSTI ID:
- 22275348
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2010, Issue 10; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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