| Diagrammatic approach to non-Gaussianity from inflation (2007) | |||||||||
Abstract | |||||||||
| We present Feynman type diagrams for calculating the n-point function of the primordial curvature perturbation in terms of scalar field perturbations during inflation. The diagrams can be used to evaluate the corresponding terms in the n-point function at tree level or any required loop level. Rules are presented for drawing the diagrams and writing down the corresponding terms in real space and Fourier space. We show that vertices can be renormalised to automatically account for diagrams with dressed vertices. We apply these rules to calculate the primordial power spectrum up to two loops, the bispectrum including loop corrections, and the trispectrum.. Comment: 17 pages, 13 figures. v2: Comments and references added, v3: Introduction expanded, subsection on evaluating loop diagrams added, minor errors corrected, references added | |||||||||
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