Form of axion in DFSZ models with $U(1)_{PQ}$ symmetry

TL;DR

This paper determines the form of the axion in DFSZ models with $U(1)_{PQ}$ symmetry by diagonalizing the mass matrix and applying the PQ mechanism, analyzing couplings, and decay processes of the axion.

Contribution

It provides a consistent method to define the axion form in DFSZ models using mass matrix diagonalization and PQ charge constraints, including analysis of axion couplings and decay channels.

Findings

Consistent axion form derived from mass matrix diagonalization.

Re-examination of axion-photon-photon couplings.

Analysis of axion decay into photon pairs.

Abstract

Form of axion state in the DFSZ model is determined by exacted diagonalizing of the mass mixing matrix of $CP$-odd sector. After applying $PQ$ mechanism to determine $PQ$ charges of particles of the model, these $PQ$ charges are used to define the general form of axion. Both of these two methods give consistent and reasonable physical state of axion. The constraint of $PQ$ charge in $DFSZ - I$ model is also pointed out. Then, anomalous couplings of axion-photon-photon is re-examined. Triple-couplings of axion with two fermions are studied. The decay of and axion into a pair of photon is also considered via re-normalizable interactions arising from kinetic terms of scalar fields.