Axions in gravity with torsion

TL;DR

This paper explores axions arising from gravity with torsion, showing their equivalence and discussing their phenomenology, which is governed by the Planck scale and has implications for astrophysics and cosmology.

Contribution

It demonstrates the equivalence of the Kalb-Ramond and Barbero-Immirzi axions in gravity with torsion and analyzes their phenomenological implications.

Findings

Torsion-related axions are equivalent in effective theory.

These axions are extremely light and weakly interacting.

Phenomenology is determined solely by the Planck scale.

Abstract

We study a scenario allowing a solution of the strong charge parity problem via the Peccei-Quinn mechanism, implemented in gravity with torsion. In this framework there appears a torsion-related pseudoscalar field known as Kalb-Ramond axion. We compare it with the so-called Barbero-Immirzi axion recently proposed in the literature also in the context of the gravity with torsion. We show that they are equivalent from the viewpoint of the effective theory. The phenomenology of these torsion-descended axions is completely determined by the Planck scale without any additional model parameters. These axions are very light and very weakly interacting with ordinary matter. We briefly comment on their astrophysical and cosmological implications in view of the recent BICEP2 and Planck data.