Supernova Explosion and Neutral Currents of Weak Interaction

Diffusion of neutrinos in supernova core is investigated on the basis of the Weinberg theory of weak interaction. Escape rates of neutrinos and hydrodynamic collapse of the core are computed simultaneously on the assumption that supernova core is homogeneous (one-shell model). Computations are carried out for a number of sets of initial core temperatures, Ti = 109.5 and 1010K and the Weinberg angles, sin2θW = 0.45, 0.3 and 0. The initial core density and mass are fixed as 109.5g/cm3 and 1.26 M⊙ (Chandrasekhar mass of iron star), respectively. We have obtained the following results. 1) The core becomes opaque to neutrinos before electron captures of nuclei proceed sufficiently, and neutrinos are confined in the core. Therefore neutralization of the nuclei is strongly suppressed by the Pauli principle of degenerate neutrino sea and by neutrino captures (the inverse process of electron captures), compared with the cases under the usual CVC theory. 2) The greater we assume the value of the Weinberg angle, the more neutrinos are confined and the collapse bounces at the lower density due to the pressure of confined leptons. 3) Features of bounce depend on the initial core temperature strongly compared with the cases under the usual CVC theory. 4) Under the neutral current theory, a supernova core will bounce by thermal pressure gradient instead of nuclear repulsive force.