In-in and δN calculations of the bispectrum from non-attractor single-field inflation
- Centre for Theoretical Cosmology, DAMTP, University of Cambridge, Cambridge, CB3 0WA (United Kingdom)
- School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
- Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str. 1, Garching, 85741 (Germany)
- School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
- Yukawa Institute for theoretical Physics, Kyoto University, Kyoto, 606–8502 (Japan)
In non-attractor single-field inflation models producing a scale-invariant power spectrum, the curvature perturbation on super-horizon scales grows as R∝a{sup 3}. This is so far the only known class of self-consistent single-field models with a Bunch-Davies initial state that can produce a large squeezed-limit bispectrum violating Maldacena's consistency relation. Given the importance of this result, we calculate the bispectrum with three different methods: using quantum field theory calculations in two different gauges, and classical calculations (the δN formalism). All the results agree, giving the local-form bispectrum parameter of f{sup local}{sub NL} = 5(1+c{sub s}{sup 2})/(4c{sub s}{sup 2}). This result is valid for arbitrary values of the speed of sound parameter, c{sub s}, for a particular non-attractor model we consider in this paper.
- OSTI ID:
- 22369857
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2013, Issue 12; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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