Axion-Higgs Unification

TL;DR

This paper proposes a composite Higgs and axion model within a strong gauge dynamics framework, naturally realizing KSVZ and DFSZ axion models, and addressing multiple fundamental issues in particle physics.

Contribution

It introduces a unified composite framework for Higgs and axion, explaining their properties and related phenomena from strong dynamics without fundamental scalars.

Findings

Axion solves QCD theta problem and matches dark matter abundance.

Higgs mass generated via RGE effects from small quartic coupling.

Gauge couplings can unify with extra fermions.

Abstract

In theories with no fundamental scalars, one gauge group can become strong at a large scale Lambda and spontaneously break a global symmetry, producing the Higgs and the axion as composite pseudo-Nambu-Goldstone bosons. We show how KSVZ and DFSZ axion models can be naturally realised. The assumption Lambda around 10^{11} GeV is phenomenologically favoured because: a) The axion solves the QCD theta problem and provides the observed DM abundance; b) The observed Higgs mass is generated via RGE effects from a small Higgs quartic coupling at the compositeness scale, provided that the Higgs mass term is fine-tuned to be of electroweak size; c) Lepton, quark as well as neutrino masses can be obtained from four-fermion operators at the compositeness scale. d) The extra fermions can unify the gauge couplings.