A comprehensive study of axion photoproduction off the nucleon in chiral effective field theory

TL;DR

This paper calculates axion photoproduction amplitudes off nucleons using chiral effective field theory, including various contributions, to aid in distinguishing axion models through cross section analysis.

Contribution

It provides a comprehensive calculation of axion photoproduction amplitudes incorporating multiple mechanisms within chiral effective field theory, enhancing understanding of axion-nucleon interactions.

Findings

Different mechanisms produce distinct cross section behaviors.

The study offers phenomenological insights for axion model discrimination.

Utilizes existing hadronic inputs to constrain unknown couplings.

Abstract

We calculate the amplitudes of the axion photoproduction off the nucleon, i.e., $\gamma N \to a N$, within the framework of chiral effective field theory. Several different types of contributions are simultaneously included in our calculation, namely the nucleon exchanges up to next-to-leading order, the $a\gamma\gamma$ vertex and the vector meson exchanges in the $t$-channel. We utilize the existing hadronic inputs as much as possible to fix the unknown couplings. A comprehensive study of the phenomenological discussions is then provided in this work. Different mechanisms in the $\gamma N \to a N$ processes manifest distinct behaviors in the total and differential cross sections, which could provide useful quantities to distinguish different axion models.