# Constraints on single-field inflation

## Abstract

Many alternatives to canonical slow-roll inflation have been proposed over the years, one of the main motivations being to have a model, capable of generating observable values of non-Gaussianity. In this work, we (re-)explore the physical implications of a great majority of such models within a single, effective field theory framework (including novel models with large non-Gaussianity discussed for the first time below). The constraints we apply — both theoretical and experimental — are found to be rather robust, determined to a great extent by just three parameters: the coefficients of the quadratic EFT operators (δN){sup 2} and δNδE, and the slow-roll parameter ε. This allows to significantly limit the majority of single-field alternatives to canonical slow-roll inflation. While the existing data still leaves some room for most of the considered models, the situation would change dramatically if the current upper limit on the tensor-to-scalar ratio decreased down to r<10{sup −2}. Apart from inflationary models driven by plateau-like potentials, the single-field model that would have a chance of surviving this bound is the recently proposed slow-roll inflation with weakly-broken galileon symmetry. In contrast to canonical slow-roll inflation, the latter model can support r<10{sup −2} even if driven by a convexmore »

- Authors:

- Institut de Théorie des Phénoménes Physiques,EPFL Lausanne (Switzerland)
- Scuola Normale Superiore,Piazza dei Cavalieri 7, 56126, Pisa (Italy)
- (Italy)

- Publication Date:

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

- OSTI Identifier:
- 22572107

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2016; Journal Issue: 06; Other Information: PUBLISHER-ID: JCAP06(2016)051; OAI: oai:repo.scoap3.org:16189; 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; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMOLOGICAL INFLATION; FIELD OPERATORS; INFLATIONARY UNIVERSE; POTENTIALS; QUANTUM FIELD THEORY; SCALAR FIELDS; SYMMETRY BREAKING; TENSOR FIELDS

### Citation Formats

```
Pirtskhalava, David, Santoni, Luca, Trincherini, Enrico, and INFN - Sezione di Pisa,56200, Pisa.
```*Constraints on single-field inflation*. United States: N. p., 2016.
Web. doi:10.1088/1475-7516/2016/06/051.

```
Pirtskhalava, David, Santoni, Luca, Trincherini, Enrico, & INFN - Sezione di Pisa,56200, Pisa.
```*Constraints on single-field inflation*. United States. doi:10.1088/1475-7516/2016/06/051.

```
Pirtskhalava, David, Santoni, Luca, Trincherini, Enrico, and INFN - Sezione di Pisa,56200, Pisa. Tue .
"Constraints on single-field inflation". United States.
doi:10.1088/1475-7516/2016/06/051.
```

```
@article{osti_22572107,
```

title = {Constraints on single-field inflation},

author = {Pirtskhalava, David and Santoni, Luca and Trincherini, Enrico and INFN - Sezione di Pisa,56200, Pisa},

abstractNote = {Many alternatives to canonical slow-roll inflation have been proposed over the years, one of the main motivations being to have a model, capable of generating observable values of non-Gaussianity. In this work, we (re-)explore the physical implications of a great majority of such models within a single, effective field theory framework (including novel models with large non-Gaussianity discussed for the first time below). The constraints we apply — both theoretical and experimental — are found to be rather robust, determined to a great extent by just three parameters: the coefficients of the quadratic EFT operators (δN){sup 2} and δNδE, and the slow-roll parameter ε. This allows to significantly limit the majority of single-field alternatives to canonical slow-roll inflation. While the existing data still leaves some room for most of the considered models, the situation would change dramatically if the current upper limit on the tensor-to-scalar ratio decreased down to r<10{sup −2}. Apart from inflationary models driven by plateau-like potentials, the single-field model that would have a chance of surviving this bound is the recently proposed slow-roll inflation with weakly-broken galileon symmetry. In contrast to canonical slow-roll inflation, the latter model can support r<10{sup −2} even if driven by a convex potential, as well as generate observable values for the amplitude of non-Gaussianity.},

doi = {10.1088/1475-7516/2016/06/051},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 06,

volume = 2016,

place = {United States},

year = {Tue Jun 28 00:00:00 EDT 2016},

month = {Tue Jun 28 00:00:00 EDT 2016}

}