QCD Axion From a Spontaneously Broken B-L Gauge Symmetry

TL;DR

This paper proposes a model where the QCD axion arises from a spontaneously broken B-L gauge symmetry, ensuring a high-quality Peccei-Quinn symmetry compatible with supersymmetry and cosmological constraints.

Contribution

It introduces a simple B-L extension of the MSSM that naturally realizes a high-quality PQ symmetry as a remnant of gauge symmetry, with a light gravitino mass compatible with cosmology.

Findings

Peccei-Quinn symmetry is a remnant of B-L gauge symmetry.

A light gravitino mass (~1 eV) is compatible with high reheating temperatures.

Potential testability via future 21cm line observations.

Abstract

In this paper, we show that the Peccei-Quinn (PQ) symmetry with a good quality can be realized in a simple $B-L$ extension of the minimal supersymmetric standard model. The PQ symmetry is a remnant of the $B-L$ gauge symmetry at the renormalizable level. Besides, the sufficient quality of the PQ symmetry is preserved by a non anomalous discrete gauged $R$-symmetry and a small gravitino mass $m_{3/2}\ll 100$GeV. A viable mass range is $m_{3/2}=\mathcal{O}(1)$eV which allows a high reheating temperature and many baryogenesis scenarios typified by the thermal leptogenesis without any astrophysical and cosmological problems. Such a light gravitino may be tested in the future 21cm line observations.