A natural and simple UV completion of the QCD axion model

Masaki Yamada,Tsutomu T Yanagida

doi:10.1016/j.physletb.2021.136267

Masaki Yamada, Tsutomu T Yanagida

Open Access

https://doi.org/10.1016/j.physletb.2021.136267

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Abstract

The novel PQ mechanism replaces the strong CP problem with some challenges in a model building. In particular, the challenges arise regarding i) the origin of an anomalous global symmetry called a PQ symmetry, ii) the scale of the PQ symmetry breaking, and iii) the quality of the PQ symmetry. In this letter, we provide a natural and simple UV completed model that addresses these challenges. Extra quarks and anti-quarks are separated by two branes in the Randall-Sundrum R4×S1/Z2 spacetime while a hidden SU(NH) gauge field condensates in the bulk. The brane separation is the origin of the PQ symmetry and its breaking scale is given by the dynamical scale of the SU(NH) gauge interaction. The (generalized) Casimir force of SU(NH) condensation stabilizes the 5th dimension, which guarantees the quality of the PQ symmetry.

Highlights

We provide a simple UV model that naturally realizes the PQ mechanism, combining the ideas proposed in Refs. [42, 51]
Such a “small” energy scale of fa is naturally realized in our model due to the dimensional transmutation
This implies that if one wants to consider a grand unified theory (GUT), the PQ scale should be as large as the GUT scale

Summary

UV brane

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

IR brane

Brane tension

Warp factor

Casimir force

FAB F AB