Consistency relation for the Lorentz invariant single-field inflation
- Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China)
In this paper we compute the sizes of equilateral and orthogonal shape bispectrum for the general Lorentz invariant single-field inflation. The stability of field theory implies a non-negative square of sound speed which leads to a consistency relation between the sizes of orthogonal and equilateral shape bispectrum, namely f{sub NL}{sup orth.} ≤ −0.054f{sub NL}{sup equil.}. In particular, for the single-field Dirac-Born-Infeld (DBI) inflation, the consistency relation becomes f{sub NL}{sup orth.} = 0.070f{sub NL}{sup equil.} ≤ 0. These consistency relations are also valid in the mixed scenario where the quantum fluctuations of some other light scalar fields contribute to a part of total curvature perturbation on the super-horizon scale and may generate a local form bispectrum. A distinguishing prediction of the mixed scenario is τ{sub NL}{sup loc.} > ((6/5)f{sub NL}{sup loc.}){sup 2}. Comparing these consistency relations to WMAP 7yr data, there is still a big room for the Lorentz invariant inflation, but DBI inflation has been disfavored at more than 68% CL.
- OSTI ID:
- 22272879
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2010, Issue 05; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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