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 7 Li and 11 B is significantly enhanced through the ν-process 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 7 Li, 11 B, and other isotopes produced in supernovae. We evaluate the 7 Li and 11 B 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 θ 13 . In the case of a normal mass hierarchy and an adiabatic resonance of 13-mixing, the 7 Li yield is larger than that without neutrino oscillations by a factor of ∼ 2. For other parameter cases and for the 11 B yield in general, the enhancement is smaller. The increase of the 7 Li/ 11 B ratio is demonstrated for a normal mass hierarchy and a relatively large sin 2 2θ 13 , where 13-mixing resonance is adiabatic and sin 2 2θ 13 < 0.1. Thus, the detection of 7 Li/ 11 B enhancements in stars showing signs of supernova enrichment suggest a normal mass hierarchy and relatively large value of sin 2 2θ 13 .