Thermal interpretation of infrared dynamics in de Sitter

Journal Article · Fri Jul 01 04:00:00 EDT 2016 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2016/07/035· OSTI ID:22679640

Rigopoulos, Gerasimos ^[1]

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1. School of Mathematics and Statistics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU U.K. (United Kingdom)

The infrared dynamics of a light, minimally coupled scalar field in de Sitter spacetime with Ricci curvature R = 12 H {sup 2}, averaged over horizon sized regions of physical volume V {sub H} = (4π/3)(1/ H ){sup 3}, can be interpreted as Brownian motion in a medium with de Sitter temperature T {sub DS} = h-bar H /2π. We demonstrate this by directly 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 T {sub DS} 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 ∂{sub μ}φ and takes a well defined value per horizon volume ½((∇φ){sup 2}) = − ½ T {sub DS}/ V {sub H} . This approach allows for the non-perturbative computation of the de Sitter invariant stress energy tensor ( T {sub μν}) for an arbitrary scalar potential.

• OSTI ID: 22679640
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 07 Vol. 2016; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BROWNIAN MOVEMENT
CALCULATION METHODS
D S MESONS
DE SITTER GROUP
DE SITTER SPACE
DISTRIBUTION
EQUILIBRIUM
FLUCTUATIONS
INFLATIONARY UNIVERSE
RICCI TENSOR
SCALAR FIELDS
SPACE-TIME
STOCHASTIC PROCESSES