# Conflation: a new type of accelerated expansion

## Abstract

In the framework of scalar-tensor theories of gravity, we construct a new kind of cosmological model that conflates inflation and ekpyrosis. During a phase of conflation, the universe undergoes accelerated expansion, but with crucial differences compared to ordinary inflation. In particular, the potential energy is negative, which is of interest for supergravity and string theory where both negative potentials and the required scalar-tensor couplings are rather natural. A distinguishing feature of the model is that, for a large parameter range, it does not significantly amplify adiabatic scalar and tensor fluctuations, and in particular does not lead to eternal inflation and the associated infinities. We also show how density fluctuations in accord with current observations may be generated by adding a second scalar field to the model. Conflation may be viewed as complementary to the recently proposed anamorphic universe of Ijjas and Steinhardt.

- Authors:

- Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute),Am Mühlenberg 1, Potsdam-Golm, 14476 (Germany)

- Publication Date:

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

- OSTI Identifier:
- 22572142

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2016; Journal Issue: 08; Other Information: PUBLISHER-ID: JCAP08(2016)073; OAI: oai:repo.scoap3.org:16998; 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:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COSMOLOGICAL INFLATION; COSMOLOGY; EXPANSION; INFLATIONARY UNIVERSE; POTENTIAL ENERGY; SCALAR FIELDS; STRING THEORY; UNIVERSE

### Citation Formats

```
Fertig, Angelika, Lehners, Jean-Luc, and Mallwitz, Enno.
```*Conflation: a new type of accelerated expansion*. United States: N. p., 2016.
Web. doi:10.1088/1475-7516/2016/08/073.

```
Fertig, Angelika, Lehners, Jean-Luc, & Mallwitz, Enno.
```*Conflation: a new type of accelerated expansion*. United States. doi:10.1088/1475-7516/2016/08/073.

```
Fertig, Angelika, Lehners, Jean-Luc, and Mallwitz, Enno. Wed .
"Conflation: a new type of accelerated expansion". United States.
doi:10.1088/1475-7516/2016/08/073.
```

```
@article{osti_22572142,
```

title = {Conflation: a new type of accelerated expansion},

author = {Fertig, Angelika and Lehners, Jean-Luc and Mallwitz, Enno},

abstractNote = {In the framework of scalar-tensor theories of gravity, we construct a new kind of cosmological model that conflates inflation and ekpyrosis. During a phase of conflation, the universe undergoes accelerated expansion, but with crucial differences compared to ordinary inflation. In particular, the potential energy is negative, which is of interest for supergravity and string theory where both negative potentials and the required scalar-tensor couplings are rather natural. A distinguishing feature of the model is that, for a large parameter range, it does not significantly amplify adiabatic scalar and tensor fluctuations, and in particular does not lead to eternal inflation and the associated infinities. We also show how density fluctuations in accord with current observations may be generated by adding a second scalar field to the model. Conflation may be viewed as complementary to the recently proposed anamorphic universe of Ijjas and Steinhardt.},

doi = {10.1088/1475-7516/2016/08/073},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 08,

volume = 2016,

place = {United States},

year = {Wed Aug 31 00:00:00 EDT 2016},

month = {Wed Aug 31 00:00:00 EDT 2016}

}