Exploring the Neutrino Mass Hierarchy from Isotopic Ratios of Supernova Nucleosynthesis Products in Presolar Grains

초록

We study the nucleosynthesis in a core-collapse supernova (CCSN) model including newly calculated neutrino-induced reaction rates with both collective and Mikheyev-Smirnov-Wolfenstein neutrino flavor oscillations considered. We show that the measurement of a pair of 11B/10B and 138La/139La or 6Li/7Li and 138La/139La in presolar grains that are inferred to have originated from CCSNs could constrain the neutrino mass hierarchy. The new shell model and the model of quasiparticle random phase approximation in the estimate of three important neutrino-induced reactions, nu + 16O, nu + 20Ne, and nu + 138Ba, are applied in our reaction network. The new rates decrease the calculated 7Li/6Li ratio by a factor of 5 compared with the previous study. More interestingly, these new rates result in a clear separation of the isotopic ratio of 11B/10B between normal and inverted mass hierarchies in the O/Ne, O/C, and C/He layers, where 138La abundance depends strongly on the mass hierarchy. In these layers, the sensitivity of the calculated abundances of 10,11B and 6,7Li to the nuclear reaction uncertainties is also tiny. Therefore, we propose that the 11B/10B versus 138La/139La and 6Li/7Li versus 138La/139La in type X silicon carbide grains sampled material from C/He layer can be used as a new probe to constrain the neutrino mass hierarchy.

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