2000 Fiscal Year Annual Research Report

大気ニュートリノ異常に関連した物理学

Research Project

Project/Area Number	10640280
Research Institution	Tokyo Metropolitan University
Principal Investigator	安田修東京都立大学, 理学研究科, 助手 (50183116)
Co-Investigator(Kenkyū-buntansha)	梶田隆章東京大学, 宇宙線研究所, 教授 (40185773) 南方久和東京都立大学, 理学研究科, 教授 (00112475)
Keywords	大気ニュートリノ / ニュートリノ振動 / ニュートリノ質量 / レプトンのフレーバー混合
Research Abstract	安田は不毛ニュートリノを含む四種類ニュートリノ混合の(2+2)スキームと呼ばれる枠組で大気ニュートリノの解析を行い、太陽ニュートリノの新しいデータと組み合わせることにより、太陽・大気どちらも通常のニュートリノと不毛ニュートリノの振動の混成のみが許されることを示した。又、ニュートリノファクトリーと従来型の長基線実験でCP非保存の位相の測定の可能性を、全ての振動パラメーターの誤差と物質効果の不定性を考慮にいれて議論し、測定器のサイズ次第では測定可能であることを示した。一方,活動銀河核やガンマ線バーストなどの宇宙論的距離にある天体からニュートリノが伝搬している間にニュートリノのフレーバーの比がどのように変化するかを、三種類と四種類のニュートリノフレーバーの枠組により太陽・大気ニュートリノの最新のデータを考慮して議論した。南方は0.1GeVという超低エネルギーのニュートリノビームの長基線実験でのCP非保存の測定の可能性を吟味し,測定器を1Mt,ビームの強度を今のK2Kの10倍の強度と出来るならば,CP非保存が測定可能であることを示した.又,超新星からのニュートリノの観測において,ある条件のもとで,逆ヒエラルキーのニュートリノ質量パターンが観測と矛盾することを示した.梶田は大気ニュートリノのニュートリノ振動に関しては測定を一層精密にし、100%不毛ニュートリノが関与するニュートリノ振動の可能性は排除されることを示し、大気ニュートリノにおけるタウ粒子の検出に関しての仕事を発展させ,ある程度のタウ粒子を測定したと解釈出来る結果を得た.又,太陽ニュートリノに関しては昼夜の観測値の差の少なさと,エネルギースペクトラムの平坦さとから,小混合角MSW解と真空振動解が95%の信頼度で排除されることを示した.

Research Products

(18 results)

All Other

All Publications (18 results)

[Publications] H.Athar,M.Jezabek,O.Yasuda: "Effects of neutrino mixing on high-energy cosmic neutrino flux"Physical Review. D62. 103007-1-103007-8 (2000)
[Publications] O.Yasuda: "Neutrino oscillations in high energy cosmic neutrino flux"Proceedings of workshop on neutrino oscillations and their origin. 271-274 (2000)
[Publications] O.Yasuda: "Phenomenology of neutrino oscillations at a neutrino factory"Proceedings of KEK international workshop on high intensity muon sources. 107-118 (2001)
[Publications] O.Yasuda: "Analysis of the Superkamiokande atmospheric neutrino data in the framework of four neutrino mixings"Proceedings of international workshop on muon storage ring for a neutrino factory (NUFACT'OO). (発表予定). (2001)
[Publications] P.Hernandez,O.Yasuda: "Neutrino oscillation physics at a ν factory"Proceedings of international workshop on muon storage ring for a neutrino factory (NUFACT'OO). (発表予定). (2001)
[Publications] O.Yasuda: "Four neutrino oscillation analysis of atmospheric neutrino data and application to long baseline experiments"Proceedings of 30th international conference on high energy physics (ICHEP2000). (発表予定). (2001)
[Publications] O.Yasuda: "Neutrino oscillations with four generations."Proceedings of joint U.S./Japan workshop on new initiatives in lepton flavor violation and neutrino oscillations with very intense muon and neutrino sources. (発表予定). (2001)
[Publications] O.Yasuda: "Various solutions of the atmospheric neutrino data"Proceedings of 2nd workshop on neutrino oscillations and their origin (NOON2000). (発表予定). (2001)
[Publications] H.Minakata,H.Nunokawa: "Measuring leptonic CP violation by low-energy neutrino oscillation experiments"Physics Letters. B495. 369-377 (2000)
[Publications] H.Minakata: "Answering the Sphinx's questions on neutrinos"Proceedings of workshop on neutrino oscillations and their origin. 343-346 (2001)
[Publications] H.Minakata,H.Nunokawa: "Measuring CP violation by low-energy medium baseline neutrino oscillation experiments"Proceedings of international workshop on muon storage ring for a neutrino factory (NUFACT'OO). (発表予定). (2001)
[Publications] H.Minakata: "Degenerate and other neutrino mass scenarios and dark matter"Proceedings of 3rd international conference on dark matter in astro and particle physics (DARK2000). (発表予定). (2001)
[Publications] H.Minakata: "The three neutrino scenario"Proceedings of Europhysics neutrino oscillation workshop (NOW2000). (発表予定). (2001)
[Publications] H.Minakata,H.Nunokawa: "Inverted hierarchy of neutrino masses disfavored by supernova 1987a"Physics Letters. (発表予定). (2001)
[Publications] T.Kajita: "Results from Superkamiokande"Nuclear Physics (Proceedings Supplement). B85. 44-51 (2000)
[Publications] T.Kajita: "Expected sensitivity of the future atmospheric neutrino data"Proceedings of workshop on neutrino oscillations and their origin. 335-337 (2000)
[Publications] T.Kajita et al.(Superkamiokande collaboration): "Tau neutrinos favored over sterile neutrinos in atmospheric muon neutrino oscillations"Physical Review Letters. 85. 3999-4003 (2000)
[Publications] T.Kajita,Y.Totsuka: "Observation of atmospheric neutrinos"Review of Modern Physics. 73. 85-118 (2001)

2000 Fiscal Year Annual Research Report

大気ニュートリノ異常に関連した物理学

Principal Investigator

安田 修 東京都立大学, 理学研究科, 助手 (50183116)

Research Products

[Publications] H.Athar,M.Jezabek,O.Yasuda: "Effects of neutrino mixing on high-energy cosmic neutrino flux"Physical Review. D62. 103007-1-103007-8 (2000)

[Publications] O.Yasuda: "Neutrino oscillations in high energy cosmic neutrino flux"Proceedings of workshop on neutrino oscillations and their origin. 271-274 (2000)

[Publications] O.Yasuda: "Phenomenology of neutrino oscillations at a neutrino factory"Proceedings of KEK international workshop on high intensity muon sources. 107-118 (2001)

[Publications] O.Yasuda: "Analysis of the Superkamiokande atmospheric neutrino data in the framework of four neutrino mixings"Proceedings of international workshop on muon storage ring for a neutrino factory (NUFACT'OO). (発表予定). (2001)

[Publications] P.Hernandez,O.Yasuda: "Neutrino oscillation physics at a ν factory"Proceedings of international workshop on muon storage ring for a neutrino factory (NUFACT'OO). (発表予定). (2001)

[Publications] O.Yasuda: "Four neutrino oscillation analysis of atmospheric neutrino data and application to long baseline experiments"Proceedings of 30th international conference on high energy physics (ICHEP2000). (発表予定). (2001)

[Publications] O.Yasuda: "Neutrino oscillations with four generations."Proceedings of joint U.S./Japan workshop on new initiatives in lepton flavor violation and neutrino oscillations with very intense muon and neutrino sources. (発表予定). (2001)

[Publications] O.Yasuda: "Various solutions of the atmospheric neutrino data"Proceedings of 2nd workshop on neutrino oscillations and their origin (NOON2000). (発表予定). (2001)

[Publications] H.Minakata,H.Nunokawa: "Measuring leptonic CP violation by low-energy neutrino oscillation experiments"Physics Letters. B495. 369-377 (2000)

[Publications] H.Minakata: "Answering the Sphinx's questions on neutrinos"Proceedings of workshop on neutrino oscillations and their origin. 343-346 (2001)

[Publications] H.Minakata,H.Nunokawa: "Measuring CP violation by low-energy medium baseline neutrino oscillation experiments"Proceedings of international workshop on muon storage ring for a neutrino factory (NUFACT'OO). (発表予定). (2001)

[Publications] H.Minakata: "Degenerate and other neutrino mass scenarios and dark matter"Proceedings of 3rd international conference on dark matter in astro and particle physics (DARK2000). (発表予定). (2001)

[Publications] H.Minakata: "The three neutrino scenario"Proceedings of Europhysics neutrino oscillation workshop (NOW2000). (発表予定). (2001)

[Publications] H.Minakata,H.Nunokawa: "Inverted hierarchy of neutrino masses disfavored by supernova 1987a"Physics Letters. (発表予定). (2001)

[Publications] T.Kajita: "Results from Superkamiokande"Nuclear Physics (Proceedings Supplement). B85. 44-51 (2000)

[Publications] T.Kajita: "Expected sensitivity of the future atmospheric neutrino data"Proceedings of workshop on neutrino oscillations and their origin. 335-337 (2000)

[Publications] T.Kajita et al.(Superkamiokande collaboration): "Tau neutrinos favored over sterile neutrinos in atmospheric muon neutrino oscillations"Physical Review Letters. 85. 3999-4003 (2000)

[Publications] T.Kajita,Y.Totsuka: "Observation of atmospheric neutrinos"Review of Modern Physics. 73. 85-118 (2001)

安田修東京都立大学, 理学研究科, 助手 (50183116)