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arXiv · 2004.09157

The $1/N$ expansion for stochastic fields in de Sitter spacetime

G. Moreau·J. Serreau·C. Noûs
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Abstract

We propose a $1/N$ expansion of Starobinsky and Yokoyama's effective stochastic approach for light quantum fields on superhorizon scales in de Sitter spacetime. We explicitly compute the spectrum and the eigenfunctions of the Fokker-Planck operator for a O($N$)-symmetric theory with quartic selfinteraction at leading and next-to-leading orders in this expansion. We obtain simple analytical expressions valid in various nonperturbative regimes in terms of the interaction coupling constant.

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G. Moreau, J. Serreau, C. Noûs. 2020-04-20. The $1/N$ expansion for stochastic fields in de Sitter spacetime. https://doi.org/10.1103/physrevd.102.125015

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