Cosmological perturbations from stochastic gravity

Journal Article · Mon Sep 15 00:00:00 EDT 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.78.064010· OSTI ID:21254091

Roura, Albert; Verdaguer, Enric ^[1]

---

1. Theoretical Division, T-8, Los Alamos National Laboratory, M.S. B285, Los Alamos, New Mexico 87545 (United States)

In inflationary cosmological models driven by an inflaton field the origin of the primordial inhomogeneities which are responsible for large-scale structure formation are the quantum fluctuations of the inflaton field. These are usually calculated using the standard theory of cosmological perturbations, where both the gravitational and the inflaton fields are linearly perturbed and quantized. The correlation functions for the primordial metric fluctuations and their power spectrum are then computed. Here we introduce an alternative procedure for calculating the metric correlations based on the Einstein-Langevin equation which emerges in the framework of stochastic semiclassical gravity. We show that the correlation functions for the metric perturbations that follow from the Einstein-Langevin formalism coincide with those obtained with the usual quantization procedures when the scalar field perturbations are linearized. This method is explicitly applied to a simple model of chaotic inflation consisting of a Robertson-Walker background, which undergoes a quasi-de Sitter expansion, minimally coupled to a free massive quantum scalar field. The technique based on the Einstein-Langevin equation can, however, deal naturally with the perturbations of the scalar field even beyond the linear approximation, as is actually required in inflationary models which are not driven by an inflaton field, such as Starobinsky's trace-anomaly driven inflation or when calculating corrections due to nonlinear quantum effects in the usual inflaton driven models.

• OSTI ID: 21254091
• Journal Information: Physical Review. D, Particles Fields, Vol. 78, Issue 6; Other Information: DOI: 10.1103/PhysRevD.78.064010; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CHAOS THEORY
COMPUTERIZED SIMULATION
CORRECTIONS
CORRELATION FUNCTIONS
CORRELATIONS
COSMOLOGICAL MODELS
DE SITTER GROUP
DISTURBANCES
FLUCTUATIONS
GRAVITATION
GRAVITATIONAL FIELDS
INFLATION
LANGEVIN EQUATION
NONLINEAR PROBLEMS
PERTURBATION THEORY
QUANTIZATION
SCALAR FIELDS
SEMICLASSICAL APPROXIMATION
SPECTRA
STOCHASTIC PROCESSES