# Factoring the strong CP problem

## Abstract

We present a new mechanism to solve the strong CP problem using $$N\geq2$$ axions, each dynamically relaxing part of the $$\bar\theta$$ parameter. At high energies $$M\gg\Lambda_{QCD}$$ the $$SU(3)_{c}$$ group becomes the diagonal subgroup of an $$SU(3)^{N}$$ gauge group, and the non-perturbative effects in each individual $SU(3)$ factor generate a potential for the corresponding axion. The vacuum is naturally aligned to ensure $$\bar\theta=0$$ at low energies, and the masses of these axions can be much larger than for the standard QCD axion. This mechanism avoids the introduction of a discrete $$Z_2$$ symmetry and associated 'mirror' copies of the SM fermions, and also avoids the introduction and stabilization of new light colored states to modify the running of the QCD gauge coupling found in other heavy axion models. This strengthens the motivation for axion-like particles solving the strong CP problem at points beyond the standard QCD axion curve in the $$(m_a, f_a)$$ plane.

- Authors:

- Harvard Univ., Cambridge, MA (United States)
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

- 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:
- 1469012

- Report Number(s):
- arXiv:1710.04213; FERMILAB-PUB-17-500-T

Journal ID: ISSN 1029-8479; 1630478

- Grant/Contract Number:
- AC02-07CH11359

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Journal of High Energy Physics (Online)

- Additional Journal Information:
- Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2018; Journal Issue: 12; Journal ID: ISSN 1029-8479

- Publisher:
- Springer Berlin

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Anomalies in Field and String Theories; Beyond Standard Model; CP violation; Solitons Monopoles and Instantons

### Citation Formats

```
Agrawal, Prateek, and Howe, Kiel. Factoring the strong CP problem. United States: N. p., 2018.
Web. doi:10.1007/JHEP12(2018)029.
```

```
Agrawal, Prateek, & Howe, Kiel. Factoring the strong CP problem. United States. doi:10.1007/JHEP12(2018)029.
```

```
Agrawal, Prateek, and Howe, Kiel. Thu .
"Factoring the strong CP problem". United States. doi:10.1007/JHEP12(2018)029. https://www.osti.gov/servlets/purl/1469012.
```

```
@article{osti_1469012,
```

title = {Factoring the strong CP problem},

author = {Agrawal, Prateek and Howe, Kiel},

abstractNote = {We present a new mechanism to solve the strong CP problem using $N\geq2$ axions, each dynamically relaxing part of the $\bar\theta$ parameter. At high energies $M\gg\Lambda_{QCD}$ the $SU(3)_{c}$ group becomes the diagonal subgroup of an $SU(3)^{N}$ gauge group, and the non-perturbative effects in each individual $SU(3)$ factor generate a potential for the corresponding axion. The vacuum is naturally aligned to ensure $\bar\theta=0$ at low energies, and the masses of these axions can be much larger than for the standard QCD axion. This mechanism avoids the introduction of a discrete $Z_2$ symmetry and associated 'mirror' copies of the SM fermions, and also avoids the introduction and stabilization of new light colored states to modify the running of the QCD gauge coupling found in other heavy axion models. This strengthens the motivation for axion-like particles solving the strong CP problem at points beyond the standard QCD axion curve in the $(m_a, f_a)$ plane.},

doi = {10.1007/JHEP12(2018)029},

journal = {Journal of High Energy Physics (Online)},

number = 12,

volume = 2018,

place = {United States},

year = {2018},

month = {12}

}

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#### Figures / Tables:

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Figures / Tables found in this record:

*Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.*