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 {ital m}{sub {ital a}}{approx_lt}10{sup {minus}2} eV are not excluded by SN 1987A. A substantial transfer of energy in neutrino-nucleon ({nu}{ital N}) collisions is enabled which may alter the spectra of SN neutrinos relative to calculations where energy-conserving {nu}{ital N} collisions had been assumed near the neutrinosphere. {copyright} {ital 1996 The American Physical Society.}