Axion arising from warped extra-dimensional gauge fields

TL;DR

This paper demonstrates that a warped extra-dimensional gauge field setup naturally produces an axion-like particle, linking two solutions to the strong-CP problem through topological and geometric arguments.

Contribution

It introduces a novel connection between axions and extra-dimensional models, showing that warping generates a light axion-like particle without new fields.

Findings

An axion-like particle arises from warped extra-dimensional gauge fields.

The decay constant depends on the extra dimension's geometry and warping scale.

The model reproduces key features of axion physics through topological effects.

Abstract

We present a connection between two known solutions to the strong-CP problem: the standard introduction of axions and the extra-dimensional one, relying on topological arguments. Using an equivalent lower-dimensional set-up with a warped extra-dimension but without adding any new fields, it is shown that an additional light degree of freedom appears. Like an axion, it couples to the topological charge density via Fermionic loop corrections. Its decay constant is related to the geometry of the extra dimension and is suppressed by the warping scale.