Nucleon spin fluctuations and the supernova emission of neutrinos and axions

In the hot and dense medium of a supernova (SN) core, the nucleon spins fluctuate so fast that the axial-vector neutrino opacity and the axion emissivity are expected to be significantly modified. Axions with m(a) less than or similar to 10(-2) eV are not excluded by SN 1987A. A substantial transfer of energy in neutrino-nucleon (nu N) collisions is enabled which may alter the spectra of SN neutrinos relative to calculations where energy-conserving nu N collisions had been assumed near the neutrinosphere.