# On the initial condition of inflationary fluctuations

## Abstract

It is usually assumed that the inflationary fluctuations start from the Bunch-Davies (BD) vacuum and the iε prescription is used when interactions are calculated. We show that those assumptions can be verified explicitly by calculating the loop corrections to the inflationary two-point and three-point correlation functions. Those loop corrections can be resummed to exponential factors, which suppress non-BD coefficients and behave as the iε factor for the case of the BD initial condition. A new technique of loop chain diagram resummation is developed for this purpose. For the non-BD initial conditions which is setup at finite time and has not fully decayed, explicit correction to the two-point and three-point correlation functions are calculated. Especially, non-Gaussianity in the folded limit is regularized due to the interactions.

- Authors:

- Department of Physics, The Hong Kong University of Science and Technology,Clear Water Bay, Kowloon, Hong Kong (China)

- Publication Date:

- Sponsoring Org.:
- SCOAP3, CERN, Geneva (Switzerland)

- OSTI Identifier:
- 22572065

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2016; Journal Issue: 04; Other Information: PUBLISHER-ID: JCAP04(2016)041; OAI: oai:repo.scoap3.org:15317; cc-by Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CORRECTIONS; CORRELATION FUNCTIONS; COSMOLOGICAL INFLATION; COSMOLOGY; FLUCTUATIONS; INFLATIONARY UNIVERSE; PERTURBATION THEORY

### Citation Formats

```
Jiang, Hongliang, Wang, Yi, and Zhou, Siyi.
```*On the initial condition of inflationary fluctuations*. United States: N. p., 2016.
Web. doi:10.1088/1475-7516/2016/04/041.

```
Jiang, Hongliang, Wang, Yi, & Zhou, Siyi.
```*On the initial condition of inflationary fluctuations*. United States. doi:10.1088/1475-7516/2016/04/041.

```
Jiang, Hongliang, Wang, Yi, and Zhou, Siyi. Thu .
"On the initial condition of inflationary fluctuations". United States.
doi:10.1088/1475-7516/2016/04/041.
```

```
@article{osti_22572065,
```

title = {On the initial condition of inflationary fluctuations},

author = {Jiang, Hongliang and Wang, Yi and Zhou, Siyi},

abstractNote = {It is usually assumed that the inflationary fluctuations start from the Bunch-Davies (BD) vacuum and the iε prescription is used when interactions are calculated. We show that those assumptions can be verified explicitly by calculating the loop corrections to the inflationary two-point and three-point correlation functions. Those loop corrections can be resummed to exponential factors, which suppress non-BD coefficients and behave as the iε factor for the case of the BD initial condition. A new technique of loop chain diagram resummation is developed for this purpose. For the non-BD initial conditions which is setup at finite time and has not fully decayed, explicit correction to the two-point and three-point correlation functions are calculated. Especially, non-Gaussianity in the folded limit is regularized due to the interactions.},

doi = {10.1088/1475-7516/2016/04/041},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 04,

volume = 2016,

place = {United States},

year = {Thu Apr 21 00:00:00 EDT 2016},

month = {Thu Apr 21 00:00:00 EDT 2016}

}