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Article Dans Une Revue Physical Review D Année : 2003

WKB approximation for inflationary cosmological perturbations

Résumé

A new method for predicting inflationary cosmological perturbations, based on the Wentzel-Kramers-Brillouin (WKB) approximation, is presented. A general expression for the WKB scalar and tensor power spectra is derived. The main advantage of the new scheme of approximation is that it is valid even if the slow-roll conditions are violated. The method is applied to power-law inflation, which allows a comparison with an exact result. It is demonstrated that the WKB approximation predicts the spectral indices exactly and the amplitude with an error lower than 10%, even in regimes far from scale invariance. The new method of approximation is also applied to a situation where the slow-roll conditions hold. It is shown that the result obtained bears close resemblance with the standard slow-roll calculation. Finally, some possible improvements are briefly mentioned.
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hal-04111243 , version 1 (08-06-2023)

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Jérôme Martin, Dominik J. Schwarz. WKB approximation for inflationary cosmological perturbations. Physical Review D, 2003, 67, ⟨10.1103/PhysRevD.67.083512⟩. ⟨hal-04111243⟩
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