Large slow-roll corrections to the bispectrum of noncanonical inflation
- Départment de Physique Théorique, Université de Genève, 24 Quai E. Ansermet, CH-1211, Genève (Switzerland)
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)
- Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QH (United Kingdom)
Nongaussian statistics are a powerful discriminant between inflationary models, particularly those with noncanonical kinetic terms. Focusing on theories where the Lagrangian is an arbitrary Lorentz-invariant function of a scalar field and its first derivatives, we review and extend the calculation of the observable three-point function. We compute the ''next-order'' slow-roll corrections to the bispectrum in closed form, and obtain quantitative estimates of their magnitude in DBI and power-law k-inflation. In the DBI case our results enable us to estimate corrections from the shape of the potential and the warp factor: these can be of order several tens of percent. We track the possible sources of large logarithms which can spoil ordinary perturbation theory, and use them to obtain a general formula for the scale dependence of the bispectrum. Our result satisfies the next-order version of Maldacena's consistency condition and an equivalent consistency condition for the scale dependence. We identify a new bispectrum shape available at next-order, which is similar to a shape encountered in Galileon models. If f{sub NL} is sufficiently large this shape may be independently detectable.
- OSTI ID:
- 22277789
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2011, Issue 07; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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