Predictions for Nongaussianity from Nonlocal Inflation - High Energy Physics - TheoryReport as inadecuate

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Abstract: In our previous work the nonlinearity parameter f NL, which characterizesnongaussianity in the cosmic microwave background, was estimated for a class ofinflationary models based on nonlocal field theory. These models include p-adicinflation and generically have the remarkable property that slow roll inflationcan proceed even with an extremely steep potential. Previous calculations foundthat large nongaussianity is possible; however, the technical complicationsassociated with studying perturbations in theories with infinitely manyderivatives forced us to provide only an order of magnitude estimate for f NL.We reconsider the problem of computing f NL in nonlocal inflation models,showing that a particular choice of field basis and recent progress incosmological perturbation theory makes an exact computation possible. Weprovide the first quantitatively accurate computation of the bispectrum innonlocal inflation, confirming our previous claim that it can be observablylarge. We show that the shape of the bispectrum in this class of models makesit observationally distinguishable from Dirac-Born-Infeld inflation models.

Author: Neil Barnaby, James M. Cline


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