# On the possibility of large axion moduli spaces

## Abstract

We study the diameters of axion moduli spaces, focusing primarily on type IIB compactifications on Calabi-Yau three-folds. In this case, we derive a stringent bound on the diameter in the large volume region of parameter space for Calabi-Yaus with simplicial Kähler cone. This bound can be violated by Calabi-Yaus with non-simplicial Kähler cones, but additional contributions are introduced to the effective action which can restrict the field range accessible to the axions. We perform a statistical analysis of simulated moduli spaces, finding in all cases that these additional contributions restrict the diameter so that these moduli spaces are no more likely to yield successful inflation than those with simplicial Kähler cone or with far fewer axions. Further heuristic arguments for axions in other corners of the duality web suggest that the difficulty observed in http://dx.doi.org/10.1088/1475-7516/2003/06/001 of finding an axion decay constant parametrically larger than M{sub p} applies not only to individual axions, but to the diagonals of axion moduli space as well. This observation is shown to follow from the weak gravity conjecture of http://dx.doi.org/10.1088/1126-6708/2007/06/060, so it likely applies not only to axions in string theory, but also to axions in any consistent theory of quantum gravity.

- Authors:

- Jefferson Physical Laboratory, Harvard University,Cambridge, MA 02138 (United States)

- Publication Date:

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

- OSTI Identifier:
- 22454542

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 04; Other Information: PUBLISHER-ID: JCAP04(2015)049; OAI: oai:repo.scoap3.org:10102; 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:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACTION INTEGRAL; AXIONS; COSMOLOGICAL INFLATION; COSMOLOGY; DECAY; DUALITY; MATHEMATICAL SPACE; QUANTUM GRAVITY; STATISTICS; STRING THEORY

### Citation Formats

```
Rudelius, Tom.
```*On the possibility of large axion moduli spaces*. United States: N. p., 2015.
Web. doi:10.1088/1475-7516/2015/04/049.

```
Rudelius, Tom.
```*On the possibility of large axion moduli spaces*. United States. doi:10.1088/1475-7516/2015/04/049.

```
Rudelius, Tom. Tue .
"On the possibility of large axion moduli spaces". United States.
doi:10.1088/1475-7516/2015/04/049.
```

```
@article{osti_22454542,
```

title = {On the possibility of large axion moduli spaces},

author = {Rudelius, Tom},

abstractNote = {We study the diameters of axion moduli spaces, focusing primarily on type IIB compactifications on Calabi-Yau three-folds. In this case, we derive a stringent bound on the diameter in the large volume region of parameter space for Calabi-Yaus with simplicial Kähler cone. This bound can be violated by Calabi-Yaus with non-simplicial Kähler cones, but additional contributions are introduced to the effective action which can restrict the field range accessible to the axions. We perform a statistical analysis of simulated moduli spaces, finding in all cases that these additional contributions restrict the diameter so that these moduli spaces are no more likely to yield successful inflation than those with simplicial Kähler cone or with far fewer axions. Further heuristic arguments for axions in other corners of the duality web suggest that the difficulty observed in http://dx.doi.org/10.1088/1475-7516/2003/06/001 of finding an axion decay constant parametrically larger than M{sub p} applies not only to individual axions, but to the diagonals of axion moduli space as well. This observation is shown to follow from the weak gravity conjecture of http://dx.doi.org/10.1088/1126-6708/2007/06/060, so it likely applies not only to axions in string theory, but also to axions in any consistent theory of quantum gravity.},

doi = {10.1088/1475-7516/2015/04/049},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 04,

volume = 2015,

place = {United States},

year = {Tue Apr 28 00:00:00 EDT 2015},

month = {Tue Apr 28 00:00:00 EDT 2015}

}