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1996

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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/12307

Stochastic semiclassical equations for weakly inhomogeneous cosmologies

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http://dx.doi.org/10.1103/PhysRevD.53.1927

Abstract

Semiclassical Einstein-Langevin equations for arbitrary small metric perturbations conformally coupled to a massless quantum scalar field in a spatially flat cosmological background are derived. Use is made of the fact that for this problem the in-in or closed time path effective action is simply related to the Feynman-Vernon influence functional which describes the effect of the ``environment,'' the quantum field which is coarse grained here, on the ``system,'' the gravitational field which is the field of interest. This leads to identify the dissipation and noise kernels in the in-in effective action, and to derive a fluctuation-dissipation relation. A tensorial Gaussian stochastic source which couples to the Weyl tensor of the spacetime metric is seen to modify the usual semiclassical equations which can be veiwed now as mean field equsations. As a simple application we derive the correlation functions of the stochastic metric fluctuations produced in a flat spacetime with small metric perturbations due to the quantum fluctuations of the matter field coupled to these perturbations.

Subject

Gravitació, Pertorbació (Dinàmica quàntica), Cosmologia, Equacions diferencials estocàstiques, Física estadística

Subject (English)

Gravitation, Perturbation (Quantum dynamics), Cosmology, Stochastic differential equations, Statistical physics

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Articles publicats en revistes (Física de la Matèria Condensada)

Citation

CAMPOS, Antonio and VERDAGUER OMS, Enric. Stochastic semiclassical equations for weakly inhomogeneous cosmologies. Physical Review D. 1996. Vol. 53, num. 4, pags. 1927-1937. ISSN 0556-2821. [consulted: 19 of August of 2026]. Available at: https://hdl.handle.net/2445/12307

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