Stochastic Dynamics of Infrared Fluctuations in Accelerating Universe
| Autor: | Cook Hyun Kim, Hiroyuki Kitamoto, Gihyuk Cho |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Physics
High Energy Physics - Theory Cosmology and Nongalactic Astrophysics (astro-ph.CO) De Sitter space Scalar (physics) FOS: Physical sciences Semiclassical physics General Relativity and Quantum Cosmology (gr-qc) General Relativity and Quantum Cosmology Langevin equation Massless particle High Energy Physics - Theory (hep-th) Statistical physics Resummation Constant (mathematics) Quantum fluctuation Astrophysics - Cosmology and Nongalactic Astrophysics |
| Popis: | We extend investigations of infrared dynamics in accelerating universes. In the presence of massless and minimally coupled scalar fields, physical quantities may acquire growing time dependences through quantum fluctuations at super-horizon scales. From a semiclassical viewpoint, it was proposed that such infrared effects are described by a Langevin equation. In de Sitter space, the stochastic approach has been proved to be equivalent to resummation of the growing time dependences at the leading power. In this paper, we make the resummation derivation of the Langevin equation in a general accelerating universe. We first consider an accelerating universe whose slow-roll parameter is constant, and then extend the background as the slow-roll parameter becomes time dependent. The resulting Langevin equation contains a white noise term and the coefficient of each term is modified by the slow-roll parameter. Furthermore we find that the semiclassical description of the scalar fields leads to the same stochastic equation as far as we adopt an appropriate time coordinate. 20 pages |
| Databáze: | OpenAIRE |
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