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Physics related to the atmospheric neutrino anomaly

与大气中微子异常相关的物理

基本信息

批准号：
10640280
负责人：
YASUDA Osamu
金额：
$ 1.98万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640280/
关键词：
atmospheric neutrino neutrino oscillation neutrino mass lepton flavor mixing

项目摘要

Yasuda worked on analysis of the atmospheric neutrino data in the frameworks of two, three and four flavors, and showed that θ_<13> is small in the three flavor case, and that a large class of the hybrid oscillations with ν_μ【tautomer】ν_γ and ν_μ【tautomer】ν_s is still allowed. He also discussed phenomenology of long baseline experiments and neutrino factories and showed that CP violation can be enhanced due to matter effects and that signals of CP violation at neutrino factories are optimized for the baseline approximately 3000km and the muon energy 50 GeV.Minakata worked on implications of massive neutrinos to neutrinoless double beta decay experiments with Yasuda and found that a scheme with almost degenerate massive neutrinos suggested by the mixed dark matter scenario inevitably implies a positive signal in neutrinoless double beta decay experiments. He also examined the possibility of measuring CP violation in very low energy medium baseline experiments, and he worked on supernova neutrinos in the three flavor framework and showed that inverted and normal hierarchy patterns can be distinguished under a certain condition by neutrino conversion from supernovae. Kajita worked on observation of atmospheric neutrinos as a leader of the Super-Kamiokande group and they concluded that their data can be interpreted as evidence of neutrino oscillation. This work has caught a lot of attention not only from physicists but also from the media. Subsequently they gained more statistics of the data and they excluded the ν_μ【tautomer】ν_s scenario. On the other hand, the Super-Kamiokande group measured the solar neutrinos and they concluded that the large mixing angle MSW solution gives the best fit to the data. From our research results we have gained much more knowledge on neutrino oscillations coming from the mass squared difference of the atmospheric neutrinos.

安田对二味、三味和四味框架下的大气中微子数据进行了分析，结果表明，三味情况下θ_<13>较小，仍然允许大类ν_μ【互变异构体】ν_γ和ν_μ【互变异构体】ν_s的混合振荡。他还讨论了长基线实验和中微子工厂的现象学，并表明由于物质效应可以增强CP破坏，并且中微子工厂的CP破坏信号针对大约3000km的基线和50GeV的μ子能量进行了优化。Minakata与Yasuda一起研究了大质量中微子对中微子双β衰变实验的影响，并发现了一个几乎混合暗物质情景所暗示的简并大质量中微子不可避免地意味着无中微子双β衰变实验中的积极信号。他还研究了在极低能量介质基线实验中测量CP破坏的可能性，并研究了三味框架中的超新星中微子，并表明在一定条件下可以通过超新星中微子的转换来区分倒置和正常的层次结构模式。 Kajita 作为超级神冈小组的领导者致力于大气中微子的观测，他们得出的结论是，他们的数据可以解释为中微子振荡的证据。这项工作不仅引起了物理学家的广泛关注，也引起了媒体的广泛关注。随后他们获得了更多的数据统计数据，并排除了 ν_μ【互变异构体】ν_s 的情况。另一方面，Super-Kamiokande 小组测量了太阳中微子，他们得出的结论是，大混合角 MSW 解决方案最适合数据。从我们的研究结果中，我们从大气中微子的质量平方差中获得了更多关于中微子振荡的知识。