#### Document Type

Article

#### Date

12-11-2006

#### Language

English

#### Disciplines

Physics

#### Description/Abstract

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.

#### Repository Citation

Armendariz-Picon, Christian, "Why Should Primordial Perturbations be in a Vacuum State?" (2006). *Physics.* Paper 214.

http://surface.syr.edu/phy/214

#### Source

Harvested from Arxiv.org

#### Creative Commons License

This work is licensed under a Creative Commons Attribution 3.0 License.

## Additional Information

25 pages, 1 figure. Uses RevTeX4 More information at http://arxiv.org/abs/astro-ph/0612288