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

Understand

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 $\pi^-+\pi^0\rightarrow \pi^-+a$.