Axion emission from supernova with axion-pion-nucleon contact interaction

TL;DR

This paper investigates the impact of axion-pion-nucleon contact interactions on axion emission processes in supernovae, revealing significant enhancements in certain emission channels and emphasizing the importance of including these interactions in astrophysical models.

Contribution

It introduces the axion-pion-nucleon contact interaction into supernova axion emission calculations, showing its significant effect on specific processes previously neglected.

Findings

Contact interaction increases axion emissivity by a factor of 2-4 in certain processes.

The effect on the process $n+p\rightarrow n+p+a$ is negligible.

Other pion-induced processes are also discussed for their relative importance.

Abstract

We examine the axion emission from supernovae with a complete set of relevant axion couplings including the axion-pion-nucleon contact interaction which was ignored in the previous studies. Two processes are affected by the axion-pion-nucleon contact interaction, $\pi^-+p \rightarrow n + a$ and $n+p\rightarrow n+p+a$, and these processes can be the dominant source of axions for some region in the axion parameter space or in astrophysical conditions encountered inside supernovae. We find that the contact interaction can enhance the axion emissivity of $\pi^-+p \rightarrow n + a$ by a factor of $2-4$, while the effect on $n+p\rightarrow n+p+a$ is not significant. We also discuss the relative importance of other pion-induced processes such as $\pi^0+n\rightarrow n+a$ and $\pi^-+\pi^0\rightarrow \pi^-+a$.