## Inflation in a scale-invariant universe

## Abstract

A scale-invariant universe can have a period of accelerated expansion at early times: inflation. We use a frame-invariant approach to calculate inflationary observables in a scale-invariant theory of gravity involving two scalar fields: the spectral indices, the tensor-to-scalar ratio, the level of isocurvature modes, and non-Gaussianity. We show that scale symmetry leads to an exact cancellation of isocurvature modes and that, in the scale symmetry–broken phase, this theory is well described by a single scalar-field theory. Lastly, ee find the predictions of this theory strongly compatible with current observations.

- Authors:

- Univ. of Oxford, Oxford (United Kingdom)
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- ETH Zurich, Zurich (Switzerland)

- Publication Date:

- Research Org.:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)

- OSTI Identifier:
- 1437397

- Alternate Identifier(s):
- OSTI ID: 1454351

- Report Number(s):
- FERMILAB-PUB-18-079-T; arXiv:1802.06069

Journal ID: ISSN 2470-0010; PRVDAQ; 1655609; TRN: US1900321

- Grant/Contract Number:
- AC02-07CH11359

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Physical Review D

- Additional Journal Information:
- Journal Volume: 97; Journal Issue: 12; Journal ID: ISSN 2470-0010

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTRONOMY AND ASTROPHYSICS

### Citation Formats

```
Ferreira, Pedro G., Hill, Christopher T., Noller, Johannes, and Ross, Graham G. Inflation in a scale-invariant universe. United States: N. p., 2018.
Web. doi:10.1103/PhysRevD.97.123516.
```

```
Ferreira, Pedro G., Hill, Christopher T., Noller, Johannes, & Ross, Graham G. Inflation in a scale-invariant universe. United States. doi:10.1103/PhysRevD.97.123516.
```

```
Ferreira, Pedro G., Hill, Christopher T., Noller, Johannes, and Ross, Graham G. Wed .
"Inflation in a scale-invariant universe". United States. doi:10.1103/PhysRevD.97.123516. https://www.osti.gov/servlets/purl/1437397.
```

```
@article{osti_1437397,
```

title = {Inflation in a scale-invariant universe},

author = {Ferreira, Pedro G. and Hill, Christopher T. and Noller, Johannes and Ross, Graham G.},

abstractNote = {A scale-invariant universe can have a period of accelerated expansion at early times: inflation. We use a frame-invariant approach to calculate inflationary observables in a scale-invariant theory of gravity involving two scalar fields: the spectral indices, the tensor-to-scalar ratio, the level of isocurvature modes, and non-Gaussianity. We show that scale symmetry leads to an exact cancellation of isocurvature modes and that, in the scale symmetry–broken phase, this theory is well described by a single scalar-field theory. Lastly, ee find the predictions of this theory strongly compatible with current observations.},

doi = {10.1103/PhysRevD.97.123516},

journal = {Physical Review D},

number = 12,

volume = 97,

place = {United States},

year = {2018},

month = {6}

}

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Cited by: 8 works

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