The physical squeezed limit: consistency relations at order q{sup 2}
- Abdus Salam International Centre for Theoretical Physics Strada Costiera 11, 34151, Trieste (Italy)
- Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94306 (United States)
- SISSA, via Bonomea 265, 34136, Trieste (Italy)
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}.
- OSTI ID:
- 22369941
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2013, Issue 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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