Low-energy elastic neutrino-nucleon and nuclear scattering and its relevance for supernovae

Low-energy (E/sub v/<or approximately=20 MeV) elastic neutrino-nuclear scattering, from the neutron to the Fe-Ni region, is analysed by using both the conventional extension to hadrons of the Weinberg model (I) and the recent vector model (II). The calculation is relevant to supernova theory. In both models, for A>10, spin- (if any) and isospin-dependent effects are comfortably below 10% of the coherent scattering. In the case of the neutron, the cross-section for momentum transfer, when compared to that of the isoscalar current, is: i) more than one order of magnitude larger in model I; ii) about twice larger in model II. It is noted that the vector model gives more dramatic effects in the supernova 'strategy' both lowering the cross-section in the inner core and increasing it in the outer region. (16 refs).