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Title: The physical squeezed limit: consistency relations at order q{sup 2}

In single-field models of inflation the effect of a long mode with momentum q reduces to a diffeomorphism at zeroth and first order in q. This gives the well-known consistency relations for the n-point functions. At order q{sup 2} the long mode has a physical effect on the short ones, since it induces curvature, and we expect that this effect is the same as being in a curved FRW universe. In this paper we verify this intuition in various examples of the three-point function, whose behaviour at order q{sup 2} can be written in terms of the power spectrum in a curved universe. This gives a simple alternative understanding of the level of non-Gaussianity in single-field models. Non-Gaussianity is always parametrically enhanced when modes freeze at a physical scale k{sub ph, f} shorter than H: f{sub NL} ∼ (k{sub ph, f}/H){sup 2}.
Authors:
 [1] ; ;  [2] ; ;  [3]
  1. Abdus Salam International Centre for Theoretical Physics Strada Costiera 11, 34151, Trieste (Italy)
  2. Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94306 (United States)
  3. SISSA, via Bonomea 265, 34136, Trieste (Italy)
Publication Date:
OSTI Identifier:
22369941
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DIAGRAMS; FUNCTIONS; INFLATIONARY UNIVERSE; SPECTRA; UNIVERSE