Factoring the strong CP problem

By P. Agrawal, K. Howe. Journal of High Energy Physics, 2017

134 citations recorded by the source corpus.

We present a new mechanism to solve the strong CP problem using N ≥ 2 axions, each dynamically relaxing part of the θ parameter. At high energies M ≫ ΛQCD 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 θ¯=0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{\theta} = 0 $$\end{document} 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 Z2 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 (ma, fa) plane.

Subfields: Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7f54488b90927cc98f42be791f664b55b3624935

How researchers see this paper

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In Atomic and Molecular Physics, and Optics

1. Luca Visinelli
2. A. Hook

In Nuclear and High Energy Physics

1. Luca Visinelli
2. M. Bauer
3. L. Luzio
4. E. Nardi
5. A. Hook
6. A. Thamm
7. M. Neubert
8. Maurizio Giannotti

Citations in the corpus

• TASI Lectures on the Strong CP Problem and Axions (2018, methodology): “The second way to increase the axion mass is to use QCD itself to give the axion a second contribution to its mass [73, 74, 75, 76, 77, 78, 79] using UV instantons.”
• The landscape of QCD axion models (2020, background): “Another proposal that avoids the introduction of the discrete Z2 symmetry was put forth in [625] (see also [626, 627]).”
• Axion-like particles at future colliders (2018, result): “This is instructive to relate results obtained for the ALP with analogous, and maybe more familiar, Models in which the SM gauge symmetry is extended can also lead to larger ALP masses [47, 60–65].”