A covariant description of the interactions of axion-like particles and hadrons

TL;DR

This paper develops a covariant framework to analyze axion-like particles (ALPs) interactions with hadrons, providing invariant coupling combinations and decay rate calculations applicable across various ALP masses.

Contribution

It introduces a covariant approach that identifies invariant coupling combinations and computes decay rates for ALPs with arbitrary gluon and quark couplings.

Findings

Derived invariant coupling combinations under quark redefinitions.

Provided decay rate formulas valid for broad ALP mass ranges.

Compared new decay rate expressions with previous models.

Abstract

We present a covariant framework for analyzing the interactions and decay rates of axion-like particles (ALPs) that couple to both gluons and quarks. We identify combinations of couplings that are invariant under quark-field redefinitions, and use them to obtain physical expressions for the prominent decay rates of such ALPs, which are compared with previous calculations for scenarios where ALPs couple exclusively to quarks or to gluons. Our framework can be used to obtain ALP decay rates for arbitrary ALP couplings to gluons and quarks across a broad range of ALP masses.