期刊
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
卷 -, 期 7, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/1475-7516/2011/07/032
关键词
inflation; non-gaussianity; physics of the early universe; cosmological perturbation theory
资金
- SNF
- FCT [SFRH/BD/35984/2007]
- Science and Technology Facilities Council [ST/F002858/1]
- Fundação para a Ciência e a Tecnologia [SFRH/BD/35984/2007] Funding Source: FCT
- Science and Technology Facilities Council [ST/I000976/1, ST/F002858/1, ST/G000417/1] Funding Source: researchfish
- STFC [ST/G000417/1, ST/F002858/1, ST/I000976/1] Funding Source: UKRI
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(NL) is sufficiently large this shape may be independently detectable.
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