2001 Fiscal Year Annual Research Report

ニュートリノ振動現象の研究

Research Project

Project/Area Number	12047222
Research Institution	Tokyo Metropolitan University
Principal Investigator	南方久和東京都立大学, 理学研究科, 教授 (00112475)
Co-Investigator(Kenkyū-buntansha)	荒船次郎大学評価・学位授与機, 構, 教授 (80013415) 北澤敬章東京都立大学, 理学研究科, 助手 (20271158) 安田修東京都立大学, 理学研究科, 助手 (50183116) 柳田勉東京大学, 大学院・理学系研究科, 教授 (10125677)
Keywords	ニュートリノ振動 / フレーバー混合 / ニュートリノ質量 / CP非保存 / MSW効果 / 長基線ニュートリノ実験 / 超新星ニュートリノ / 不活性ニュートリノ
Research Abstract	1.超低エネルギーの長基線実験でCP位相を決定する問題で、「双確率空間におけるCP軌跡ダイアグラム」という理論的道具を導入し、(δ,Δm^2_<13>【tautomer】π-δ,-Δm^2_<13>)という近似的縮退を物質効果が部分的に解くことを指摘し、又基線長を約700kmに取ってCP位相と質量自乗差の符号を一つの実験の中で同時に決定できることを示すなど、さまざまな知見を得た。2.無ニュートリノ二重β崩壊実験でシグナルが見えたという最近の報告を信用した場合に、トリチウムのβ崩壊実験でどのようなシグナルが見えるかを他の全ての実験の制約を考慮して議論した。3.長基線実験におけるθ_<13>の決定がCP位相と質量自乗差の符号による不定性に左右されることを指摘し、ニュートリノと反ニュートリノ両方のビームエネルギーを振動長に微調整すればCP位相、質量自乗差の符号、θ_<13>の不定性を回避できることを示した。4.将来のニュートリノファクトリー実験におけるCP非対称の位相の測定の可能性を、三世代ニュートリノ混合の枠組で各混合角・質量自乗差・密度の不定性の誤差の相関とバックグラウンドの寄与を従来の取り扱いよりも遥かに注意深く見積もることによって議論した。その結果、密度の不定性が10%以上だったりバックグラウンド/シグナル比が10^<-3>以上だった場合には基線の長さ・ミューオンのエネルギーともに従来最善だと思われていた値よりも小さくなることがわかった。5.長基線実験で、基線の長さが短い場合には、物質効果が非自明な最初の2項まで無視できることを示した。6.不活性ニュートリノを含む四種類ニュートリノ混合の枠組は(2+2)-、(3+1)-スキームの両方が種々の実験により次第に不利になってきているが、不活性ニュートリノの数を2種類以上に増やしても質量自乗差がヒエラルキー条件を満たす限りやはり不利であることを一般的に示した。

Research Products

(21 results)

All Other

All Publications (21 results)

[Publications] T.Kajita, H.Minakata, H.Nunokawa: "Method for Determination of |U_<e3>| in Neutrino Oscillation Appearance Experiments"Physics Letters B.
[Publications] H.Minakata, H.Sugiyama: "Lower Bound on |U_<e3>|^2 from Single and Double Beta Decay Experiments"Physics Letters. B526. 335-344 (2002)
[Publications] H.Minakata, H.Nunokawa: "Exploring Neutrino Mixing with Low Energy Superbeams"Journal of High Energy Physics. 10. 001-033 (2001)
[Publications] H.Minakata, H.Nunokawa: "Inverted Hierarchy of Neutrino Masses Disfavored by Supernova 1987A"Physics Letters. B504. 301-308 (2001)
[Publications] H.Hiro-Oka, H.Minakata: "Pion Production by Parametric Resonance Mechanism with Quantum Back Reactions"Physical Review. C64. 044902-1-044902-8 (2001)
[Publications] O.Yasuda: "Analysis of the Superkamiokande atmospheric neutrino data in the framework of four neutrino mixings"Nuclear Instruments and Methods in Physics Research. A472. 343-347 (2001)
[Publications] O.Yasuda: "Four neutrino oscillation analysis of atmospheric neutrino data and application to long baseline experiments"Proceedings of the 30th International Conference On High-Energy Physics(ICHEP 2000). 952-954 (2001)
[Publications] O.Yasuda: "Various solutions of the atmospheric neutrino data"Proceedings of the 2nd Workshop on Neutrino Oscillations and Their Origin(NOON 2000). 134-143 (2001)
[Publications] J.Pinney, O.Yasuda: "Correlations of errors in measurements of CP violation at neutrino factories"Physical Review. D64. 093008-1-093008-16 (2001)
[Publications] O.Yasuda: "Vacuum mimicking phenomena in neutrino oscillations"Physics Letters. B516. 111-115 (2001)
[Publications] M.Chiba, T.Kamijo, M.Kawaki, A.Husain, M.Inuzuka, M.Ikeda, O.Yasuda: "Study of Salt Neutrino Detector"AIP conference proceedings. 579. 204-221 (2001)
[Publications] N.Kitazawa: "Gravitino condensation in five-brane backgrounds"Physical Review D.
[Publications] K.Ogure, J.Arafune, T.Yoshida: "Stability and experimental flux bound of fermi ball"Proceedings of the International Workshop on Particle Physics and the Early Universe(COSMO-01).
[Publications] M.Fujii, K.Hamaguchi, T.Yanagida: "Reheating temperature independence of cosmological baryon asymmetry in Affleck-Dine leptogenesis"Physical Review. D63. 123513-1-123513-9 (2001)
[Publications] Y.Imamura, T.Watari, T.Yanagida: "Semisimple group unification in the supersymmetric brane world"Physical Review. D64. 065023-1-065023-9 (2001)
[Publications] M.Fujii, K.Hamaguchi, T.Yanagida: "Affleck-Dine baryogenesis/leptogenesis with a gauged U(1)_<B-L>"Physical Review. D64. 123513-1-123513-9 (2001)
[Publications] K.Kurosawa, N.Maru, T.Yanagida: "Nonanomalous R symmetry in supersymmetric unified theories of quarks and leptons"Physics Letters. B512. 203-210 (2001)
[Publications] T.Watari, T.Yanagida: "Semisimple unification on T^6/Z_<12> orientifold in the type IIB supergravity"Physics Letters. B520. 322-330 (2001)
[Publications] T.Watari, T.Yanagida: "Supersymmetric grand unification model with the orbifold symmetry breaking in the six-dimensional supergravity"Physics Letters. B519. 164-168 (2001)
[Publications] K.Hamaguchi, H.Murayama, T.Yanagida: "Leptogenesis from n dominated early universe"Physical Review. D65. 043512-1-043512-8 (2002)
[Publications] M.Fujii, K.Hamaguchi, T.Yanagida: "Leptogenesis via LH_u flat direction with a gauged U(1)_<B-L>"Physical Review. D65. 043511-1-043511-11 (2002)

2001 Fiscal Year Annual Research Report

ニュートリノ振動現象の研究

Principal Investigator

南方 久和 東京都立大学, 理学研究科, 教授 (00112475)

Research Products

[Publications] T.Kajita, H.Minakata, H.Nunokawa: "Method for Determination of |U_<e3>| in Neutrino Oscillation Appearance Experiments"Physics Letters B.

[Publications] H.Minakata, H.Sugiyama: "Lower Bound on |U_<e3>|^2 from Single and Double Beta Decay Experiments"Physics Letters. B526. 335-344 (2002)

[Publications] H.Minakata, H.Nunokawa: "Exploring Neutrino Mixing with Low Energy Superbeams"Journal of High Energy Physics. 10. 001-033 (2001)

[Publications] H.Minakata, H.Nunokawa: "Inverted Hierarchy of Neutrino Masses Disfavored by Supernova 1987A"Physics Letters. B504. 301-308 (2001)

[Publications] H.Hiro-Oka, H.Minakata: "Pion Production by Parametric Resonance Mechanism with Quantum Back Reactions"Physical Review. C64. 044902-1-044902-8 (2001)

[Publications] O.Yasuda: "Analysis of the Superkamiokande atmospheric neutrino data in the framework of four neutrino mixings"Nuclear Instruments and Methods in Physics Research. A472. 343-347 (2001)

[Publications] O.Yasuda: "Four neutrino oscillation analysis of atmospheric neutrino data and application to long baseline experiments"Proceedings of the 30th International Conference On High-Energy Physics(ICHEP 2000). 952-954 (2001)

[Publications] O.Yasuda: "Various solutions of the atmospheric neutrino data"Proceedings of the 2nd Workshop on Neutrino Oscillations and Their Origin(NOON 2000). 134-143 (2001)

[Publications] J.Pinney, O.Yasuda: "Correlations of errors in measurements of CP violation at neutrino factories"Physical Review. D64. 093008-1-093008-16 (2001)

[Publications] O.Yasuda: "Vacuum mimicking phenomena in neutrino oscillations"Physics Letters. B516. 111-115 (2001)

[Publications] M.Chiba, T.Kamijo, M.Kawaki, A.Husain, M.Inuzuka, M.Ikeda, O.Yasuda: "Study of Salt Neutrino Detector"AIP conference proceedings. 579. 204-221 (2001)

[Publications] N.Kitazawa: "Gravitino condensation in five-brane backgrounds"Physical Review D.

[Publications] K.Ogure, J.Arafune, T.Yoshida: "Stability and experimental flux bound of fermi ball"Proceedings of the International Workshop on Particle Physics and the Early Universe(COSMO-01).

[Publications] M.Fujii, K.Hamaguchi, T.Yanagida: "Reheating temperature independence of cosmological baryon asymmetry in Affleck-Dine leptogenesis"Physical Review. D63. 123513-1-123513-9 (2001)

[Publications] Y.Imamura, T.Watari, T.Yanagida: "Semisimple group unification in the supersymmetric brane world"Physical Review. D64. 065023-1-065023-9 (2001)

[Publications] M.Fujii, K.Hamaguchi, T.Yanagida: "Affleck-Dine baryogenesis/leptogenesis with a gauged U(1)_<B-L>"Physical Review. D64. 123513-1-123513-9 (2001)

[Publications] K.Kurosawa, N.Maru, T.Yanagida: "Nonanomalous R symmetry in supersymmetric unified theories of quarks and leptons"Physics Letters. B512. 203-210 (2001)

[Publications] T.Watari, T.Yanagida: "Semisimple unification on T^6/Z_<12> orientifold in the type IIB supergravity"Physics Letters. B520. 322-330 (2001)

[Publications] T.Watari, T.Yanagida: "Supersymmetric grand unification model with the orbifold symmetry breaking in the six-dimensional supergravity"Physics Letters. B519. 164-168 (2001)

[Publications] K.Hamaguchi, H.Murayama, T.Yanagida: "Leptogenesis from n dominated early universe"Physical Review. D65. 043512-1-043512-8 (2002)

[Publications] M.Fujii, K.Hamaguchi, T.Yanagida: "Leptogenesis via LH_u flat direction with a gauged U(1)_<B-L>"Physical Review. D65. 043511-1-043511-11 (2002)

南方久和東京都立大学, 理学研究科, 教授 (00112475)