REDUCTION OF WEAK INTERACTION RATES IN NEUTRON-STARS BY NUCLEON SPIN FLUCTUATIONS - DEGENERATE CASE

Nucleon spin fluctuations in a dense medium reduce the ''naive'' value s of weak interaction rates (neutrino opacities, neutrino emissivities ). We extend previous studies of this effect to the degenerate case wh ich is appropriate for neutron stars a few ten seconds after formation . If neutron-neutron interactions by a one-pion exchange potential are the dominant cause of neutron spin fluctuations, a perturbative calcu lation of weak interaction rates is justified for T less than or equal to 3m/(4 pi alpha(pi)(2))approximate to 1 MeV, where m is the neutron mass and alpha(pi)approximate to 15 the pion fine-structure constant. At higher temperatures, the application of Landau's theory of Fermi l iquids is no longer justified; i.e., the neutrons cannot be viewed as simple quasiparticles in any obvious sense.