Toggle Main Menu Toggle Search

Open Access padlockePrints

Thermal Interpretation of Infrared Dynamics in de Sitter

Lookup NU author(s): Dr Gerasimos Rigopoulos

Downloads


Licence

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


Abstract

The infrared dynamics of a light, minimally coupled scalar field in de Sitter spacetime with Ricci curvature R=12HR=12H, averaged over horizon sized regions of physical volume VH=4π3(1H)3VH=4π3(1H)3, can be interpreted as Brownian motion in a medium with de Sitter temperature TDS=ℏH2πTDS=ℏH2π. We demonstrate this by employing path integral techniques, deriving the effective action of scalar field fluctuations with wavelengths larger than the de Sitter curvature radius and generalizing Starobinsky's seminal results on stochastic inflation. The effective action describes stochastic dynamics and the fluctuating force drives the field to an equilibrium characterized by a thermal Gibbs distribution at temperature TDSTDS which corresponds to a de Sitter invariant state. Hence, approach towards this state can be interpreted as thermalization. We show that the stochastic kinetic energy of the coarse-grained description corresponds to the norm of ∂μϕ∂μϕ and takes a well defined value per horizon volume 12⟨(∇ϕ)2⟩=−12TDS/VH12⟨(∇ϕ)2⟩=−12TDS/VH. This approach allows for the non-perturbative computation of the de Sitter invariant stress energy tensor ⟨Tμν⟩⟨Tμν⟩ for an arbitrary scalar potential. The infrared dynamics of a light, minimally coupled scalar field in de Sitter spacetime with Ricci curvature R=12HR=12H, averaged over horizon sized regions of physical volume VH=4π3(1H)3VH=4π3(1H)3, can be interpreted as Brownian motion in a medium with de Sitter temperature TDS=ℏH2πTDS=ℏH2π. We demonstrate this by employing path integral techniques, deriving the effective action of scalar field fluctuations with wavelengths larger than the de Sitter curvature radius and generalizing Starobinsky's seminal results on stochastic inflation. The effective action describes stochastic dynamics and the fluctuating force drives the field to an equilibrium characterized by a thermal Gibbs distribution at temperature TDSTDS which corresponds to a de Sitter invariant state. Hence, approach towards this state can be interpreted as thermalization. We show that the stochastic kinetic energy of the coarse-grained description corresponds to the norm of ∂μϕ∂μϕ and takes a well defined value per horizon volume 12⟨(∇ϕ)2⟩=−12TDS/VH12⟨(∇ϕ)2⟩=−12TDS/VH. This approach allows for the non-perturbative computation of the de Sitter invariant stress energy tensor ⟨Tμν⟩⟨Tμν⟩ for an arbitrary scalar potential.


Publication metadata

Author(s): Rigopoulos G

Publication type: Article

Publication status: Published

Journal: Journal of Cosmology and Astroparticle Physics

Year: 2016

Volume: 2016

Issue: 07

Online publication date: 21/07/2016

Acceptance date: 05/07/2016

Date deposited: 28/07/2016

ISSN (electronic): 1475-7516

Publisher: Institute of Physics Publishing Ltd.

URL: http://dx.doi.org/10.1088/1475-7516/2016/07/035

DOI: 10.1088/1475-7516/2016/07/035

Notes: JCAP07(2016)035 The paper is also available from the arxiv at http://arxiv.org/abs/1604.04313


Altmetrics

Altmetrics provided by Altmetric


Actions

Find at Newcastle University icon    Link to this publication


Share