Improved axion emissivity from a supernova via nucleon-nucleon bremsstrahlung

Understand

The most efficient axion production mechanism in a supernova (SN) core is the nucleon-nucleon bremsstrahlung.

• This process has been often modeled at the level of the vacuum one-pion exchange (OPE) approximation.
• Starting from this naive recipe, we revise the calculation including systematically different effects, namely a non-vanishing mass for the exchanged pion, the contribution from the two-pions exchange, effective in-medium nucleon masses and multiple nucleon scatterings.
• Moreover, we allow for an arbitrary degree of nucleon degeneracy.