2008/02/29 by Neil Barnaby, James M. Cline, James M Cline
Mathematics · Physics and Astronomy · #Cosmology and Gravitation Theories #Noncommutative and Quantum Gravity Theories #advanced mathematical theories #astro-ph #hep-ph #hep-th
paper · pdf · doi:10.1088/1475-7516/2008/06/030
published as JCAP 0806:030,2008 · 26 pages, 5 figures; references added, sign convention for f_NL clarified, minor corrections
arxiv created 2008/05/29 · openalex publication_date 2008/06/24 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/30
In our previous work the non-linearity parameter f NL , which characterizes non-Gaussianity in the cosmic microwave background, was estimated for a class of inflationary models based on non-local field theory. These models include p -adic inflation and generically have the remarkable property that slow roll inflation can proceed even with an extremely steep potential. Previous calculations found that large non-Gaussianity is possible; however, the technical complications associated with studying perturbations in theories with infinitely many derivatives forced us to provide only an order of magnitude estimate for f NL . We reconsider the problem of computing f NL in non-local inflation models, showing that a particular choice of field basis and recent progress in cosmological perturbation theory makes an exact computation possible. We provide the first quantitatively accurate computation of the bispectrum in non-local inflation, confirming our previous claim that it can be observably large. We show that the shape of the bispectrum in this class of models makes it observationally distinguishable from Dirac–Born–Infeld inflation models.