Do Finite Density Effects Jeopardize Axion Nucleophobia in Supernovae?

TL;DR

This paper investigates whether nucleophobic axion models retain their suppressed proton and neutron couplings in the dense environment of supernovae, showing that these models remain viable and the associated constraints are relaxed.

Contribution

It demonstrates that nucleophobic axion models stay viable at finite baryon densities typical of supernova cores, extending previous constraints.

Findings

Nucleophobic axion models remain viable at supernova densities.

Supernova bounds on axions are significantly relaxed in these models.

Finite density effects do not jeopardize the nucleophobic property.

Abstract

Nucleophobic axion models, wherein axion couplings to both protons and neutrons are simultaneously suppressed, can relax the stringent constraints from SN 1987A. However, it remains uncertain whether these models maintain their nucleophobic property under the influence of finite baryon density effects. These are especially relevant in astrophysical environments near saturation density, such as Supernovae (SNe). In this study, we demonstrate that the nucleophobic solution remains viable also at finite density. Furthermore, we show that the SN axion bound relaxes significantly in nucleophobic models, even when accounting for the integration over the non-homogeneous environment of the SN core.