Can Supernova Neutrino Nucleosynthesis Constrain Neutrino Oscillation Parameters?

Abstract

Recent neutrino experiment confirmed that neutrinos have finite masses and that neutrino oscillations occur. Supernova neutrinos also change their flavors propagating in the stellar material surrounding a proto-neutron star and, accordingly, change their spectral energy distributions. The nucleosynthesis of light elements such as 7Li and 11B is significantly enhanced through the νprocess in supernova explosions. Yields depend on the energy spectra of the neutrinos emitted from the proto-neutron star, so that neutrino oscillations could be crucial for the estimated yields of 7Li, 11B, and other isotopes produced in supernovae. We evaluate the 7Li and 11B yields in supernovae taking into account changes of the neutrino energy spectra due to flavor oscillations assuming large mixing angle solutions. We investigate their dependence on key parameters, such as mass hierarchies and the mixing angle θ13. In the case of a normal mass hierarchy and an adiabatic resonance of 13-mixing, the 7Li yield is larger than that without neutrino oscillations by a factor of ∼ 2. For other parameter cases and for the 11B yield in general, the enhancement is smaller. The increase of the 7Li/11B ratio is demonstrated for a normal mass hierarchy and a relatively large sin2 2θ13, where 13-mixing resonance is adiabatic and sin2 2θ13 < 0.1. Thus, the detection of 7Li/11B enhancements in stars showing signs of supernova enrichment suggest a normal mass hierarchy and relatively large value of sin2 2θ13.