# Khronon inflation

## Abstract

We study the possibility that the approximate time shift symmetry during inflation is promoted to the full invariance under time reparametrization t → t-tilde (t), or equivalently under field redefinition of the inflaton φ → φ-tilde (φ). The symmetry allows only two operators at leading order in derivatives, so that all n-point functions of scalar perturbations are fixed in terms of the power spectrum normalization and the speed of sound. During inflation the decaying mode only decays as 1/a and this opens up the possibility to violate some of the consistency relations in the squeezed limit, although this violation is suppressed by the (small) breaking of the field reparametrization symmetry. In particular one can get terms in the 3-point function that are only suppressed by 1/k{sub L} in the squeezed limit k{sub L}→0 compared to the local shape.

- Authors:

- Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy)
- ICC, University of Barcelona (IEEC-UB), Marti i Franques 1, Barcelona 08028 (Spain)
- Depto. de Física Teórica and IFIC, Universdad de Valencia-CSIC, Edificio de Institutos de Paterna, E-46980, Paterna (Valencia) (Spain)
- SISSA, via Bonomea 265, 34136, Trieste (Italy)

- Publication Date:

- OSTI Identifier:
- 22279817

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2012; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COMPARATIVE EVALUATIONS; COSMOLOGY; FIELD OPERATORS; INFLATIONARY UNIVERSE; INFLATONS; PARTICLE DECAY; PERTURBATION THEORY; SCALARS; SOUND WAVES; SYMMETRY; SYMMETRY BREAKING; VELOCITY

### Citation Formats

```
Creminelli, Paolo, Noreña, Jorge, Peña, Manuel, and Simonović, Marko, E-mail: creminel@ictp.it, E-mail: jorge.norena@icc.ub.edu, E-mail: mapeji@ific.uv.es, E-mail: marko.simonovic@sissa.it.
```*Khronon inflation*. United States: N. p., 2012.
Web. doi:10.1088/1475-7516/2012/11/032.

```
Creminelli, Paolo, Noreña, Jorge, Peña, Manuel, & Simonović, Marko, E-mail: creminel@ictp.it, E-mail: jorge.norena@icc.ub.edu, E-mail: mapeji@ific.uv.es, E-mail: marko.simonovic@sissa.it.
```*Khronon inflation*. United States. doi:10.1088/1475-7516/2012/11/032.

```
Creminelli, Paolo, Noreña, Jorge, Peña, Manuel, and Simonović, Marko, E-mail: creminel@ictp.it, E-mail: jorge.norena@icc.ub.edu, E-mail: mapeji@ific.uv.es, E-mail: marko.simonovic@sissa.it. Thu .
"Khronon inflation". United States. doi:10.1088/1475-7516/2012/11/032.
```

```
@article{osti_22279817,
```

title = {Khronon inflation},

author = {Creminelli, Paolo and Noreña, Jorge and Peña, Manuel and Simonović, Marko, E-mail: creminel@ictp.it, E-mail: jorge.norena@icc.ub.edu, E-mail: mapeji@ific.uv.es, E-mail: marko.simonovic@sissa.it},

abstractNote = {We study the possibility that the approximate time shift symmetry during inflation is promoted to the full invariance under time reparametrization t → t-tilde (t), or equivalently under field redefinition of the inflaton φ → φ-tilde (φ). The symmetry allows only two operators at leading order in derivatives, so that all n-point functions of scalar perturbations are fixed in terms of the power spectrum normalization and the speed of sound. During inflation the decaying mode only decays as 1/a and this opens up the possibility to violate some of the consistency relations in the squeezed limit, although this violation is suppressed by the (small) breaking of the field reparametrization symmetry. In particular one can get terms in the 3-point function that are only suppressed by 1/k{sub L} in the squeezed limit k{sub L}→0 compared to the local shape.},

doi = {10.1088/1475-7516/2012/11/032},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 11,

volume = 2012,

place = {United States},

year = {2012},

month = {11}

}