TY - JOUR

T1 - Why should primordial perturbations be in a vacuum state?

AU - Armendariz-Picon, C.

N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.

PY - 2007/2/1

Y1 - 2007/2/1

N2 - In order to calculate the power spectrum generated during a stage of inflation, we have to specify the quantum state of the inflaton perturbations, which is conventionally assumed to be the Bunch-Davies vacuum. We argue that this choice is justified only if the interactions of cosmological perturbations are strong enough to drive excited states toward the vacuum. We quantify this efficiency by calculating the decay probabilities of excited states to leading order in the slow-roll expansion in canonical single-field inflationary models. These probabilities are suppressed by a slow-roll parameter and the squared Planck mass, and enhanced by ultraviolet and infrared cut-offs. For natural choices of these scales decays are unlikely, and, hence, the choice of the Bunch-Davies vacuum as the state of the primordial perturbations does not appear to be warranted.

AB - In order to calculate the power spectrum generated during a stage of inflation, we have to specify the quantum state of the inflaton perturbations, which is conventionally assumed to be the Bunch-Davies vacuum. We argue that this choice is justified only if the interactions of cosmological perturbations are strong enough to drive excited states toward the vacuum. We quantify this efficiency by calculating the decay probabilities of excited states to leading order in the slow-roll expansion in canonical single-field inflationary models. These probabilities are suppressed by a slow-roll parameter and the squared Planck mass, and enhanced by ultraviolet and infrared cut-offs. For natural choices of these scales decays are unlikely, and, hence, the choice of the Bunch-Davies vacuum as the state of the primordial perturbations does not appear to be warranted.

KW - Cosmological perturbation theory

KW - Inflation

KW - Quantum field theory on curved space

KW - Trans-Planckian physics

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U2 - 10.1088/1475-7516/2007/02/031

DO - 10.1088/1475-7516/2007/02/031

M3 - Article

AN - SCOPUS:37649030672

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

SN - 1475-7516

IS - 2

M1 - 031

ER -