Decoherence during Inflation: the generation of classical inhomogeneities

TL;DR

This paper investigates how quantum fluctuations during inflation become classical inhomogeneities by analyzing decoherence processes using the influence functional and master equation, focusing on the inflaton field's long-wavelength modes.

Contribution

It introduces a detailed framework for describing the quantum-to-classical transition of inflationary fluctuations via the influence functional and master equation approach.

Findings

Decoherence times for system modes are computed and compared with inflationary time scales.

A renormalized stochastic Langevin equation for the homogeneous system-field is derived.

The influence of the environment on the power spectrum of fluctuations is analyzed.

Abstract

We show how the quantum to classical transition of the cosmological fluctuations produced during inflation can be described by means of the influence functional and the master equation. We split the inflaton field into the system-field (long-wavelength modes), and the environment, represented by its own short-wavelength modes. We compute the decoherence times for the system-field modes and compare them with the other time scales of the model. We present the renormalized stochastic Langevin equation for an homogeneous system-field and then we analyze the influence of the environment on the power spectrum for some modes in the system.