Second-order stochastic theory for self-interacting scalar fields in de Sitter spacetime

Abstract

We introduce a second-order stochastic effective theory for light scalar fields in de Sitter spacetime, extending the validity of the stochastic approach beyond the massless limit and demonstrating how it can be used to compute long-distance correlation functions non-perturbatively. The parameters of the second-order stochastic theory are determined from quantum field theory through a perturbative calculation, which is valid if the self-interaction parameter $\lambda$ satisfies $\lambda \ll m^2/H^2$, where $m$ is the scalar and $H$ is the Hubble rate. Therefore it allows stronger self-interactions than conventional perturbation theory, which is limited to $\lambda \ll m^4/H^4$ by infrared divergences. We demonstrate the applicability of the second-order stochastic theory by comparing its results with perturbative quantum field theory and overdamped stochastic calculations, and discuss the prospects of improving its accuracy with a full one-loop calculation of its parameters.

44 pages, 6 figures. Accepted for publication in Physical Review D

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Cited by in corpus (6)

• On the IR Divergences in de Sitter Space: loops, resummation and the semi-classical wavefunction
• Numerical stochastic inflation constrained by frozen noise
• Stochastic Inflation in General Relativity
• Computing First-Passage Times with the Functional Renormalisation Group
• Stochastic Inflation with Interacting Noises
• Scalar field effective potentials in de Sitter spacetime