Nucleon Spin Fluctuations and the Supernova Emission of Neutrinos and Axions

Abstract

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 $m_a\alt10^{-2}\,{\rm eV}$ are not excluded by SN~1987A. A substantial transfer of energy in neutrino-nucleon ($νN$) collisions is enabled which may alter the spectra of SN neutrinos relative to calculations where energy-conserving $νN$ collisions had been assumed near the neutrinosphere.

8 pages. REVTeX. 2 postscript figures, can be included with epsf. Small modifications of the text, a new "Note Added", and three new references. To be published in Phys. Rev. Lett