Non-Hermitian Yukawa interactions of fermions with axions: potential microscopic origin and dynamical mass generation

TL;DR

This paper reviews recent theoretical developments in models with anti-Hermitian Yukawa interactions between axions and fermions, exploring their consistency, potential microscopic origins, and implications for dynamical mass generation in quantum field theories.

Contribution

It introduces the formal framework for anti-Hermitian Yukawa interactions in field theories, discusses their consistency within PT-symmetry, and analyzes their role in dynamical mass generation for fermions and axions.

Findings

Anti-Hermitian Yukawa interactions can induce fermion and axion masses.

These interactions are consistent within PT-symmetry frameworks.

Additional anti-Hermitian couplings influence mass generation mechanisms.

Abstract

In this mini review, we discuss some recent developments regarding properties of (quantum) field-theory models containing anti-Hermitian Yukawa interactions between pseudoscalar fields (axions) and Dirac (or Majorana) fermions. Specifically, after motivating physically such interactions, in the context of string-inspired low-energy effective field theories, involving right-handed neutrinos and axion fields, we proceed to discuss their formal consistency within the so-called Parity-Time-reversal(PT)-symmetry framework, as well as dynamical mass generation, induced by the Yukawa interactions, for both fermions and axions. The Yukawa couplings are assumed weak, given that they are conjectured to have been generated by non-perturbative effects in the underlying microscopic string theory. The models under discussion contain, in addition to the Yukawa terms, also anti-Hermitian anomalous derivative couplings of the pseudoscalar fields to axial fermion currents, as well as interactions of the fermions with non-Hermitian axial backgrounds. We discuss the role of such additional couplings on the Yukawa-induced dynamically-generated masses. For the case where the fermions are right-handed neutrinos, we compare such masses with the radiative ones induced by both, the anti-Hermitian anomalous terms and the anti-Hermitian Yukawa interactions in phenomenologically relevant models.