Running effects on QCD axion phenomenology

TL;DR

This paper investigates how renormalization group effects influence QCD axion phenomenology within the DFSZ model, affecting astrophysical bounds and experimental sensitivities, with implications depending on the heavy Higgs scalar scale.

Contribution

It provides analytical expressions for RG effects on axion couplings and assesses their impact on phenomenology depending on heavy scalar mass scales.

Findings

RG effects can significantly alter axion coupling predictions.

Astrophysical and experimental bounds are affected by RG running.

Analytical formulas accurately describe RG effects across scales.

Abstract

We study the impact of renormalization group effects on QCD axion phenomenology. Focusing on the DFSZ model, we argue that the relevance of running effects for the axion couplings crucially depends on the scale where the heavier Higgs scalars are integrated out. We study the impact of these effects on astrophysical and cosmological bounds as well as on the sensitivity of helioscopes experiments such as IAXO and XENONnT, showing that they can be sizable even in the most conservative case in which the two Higgs doublets remain as light as the TeV scale. We provide simple analytical expressions that accurately fit the numerical solutions of the renormalization group equations as a function of the mass scale of the heavy scalars.