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Super-Kamiokande –I および II における 大気ニュートリノ L/E 振動解析

Super-Kamiokande –I および II における 大気ニュートリノ L/E 振動解析. 樋口 格 東京大学宇宙線研究所 他 Super-Kamiokande Collaboration. Contents. Motivation イベントサンプル SK-I,II での結果 SK-I,II combined analysis result Summary. Motivation. SK-I. m -like sub-GeV < 400 MeV. m -like sub-GeV > 400 MeV. m -like multi-GeV

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Super-Kamiokande –I および II における 大気ニュートリノ L/E 振動解析

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  1. Super-Kamiokande –I および II における大気ニュートリノ L/E 振動解析 樋口 格 東京大学宇宙線研究所 他 Super-Kamiokande Collaboration

  2. Contents • Motivation • イベントサンプル • SK-I,II での結果 • SK-I,II combined analysis result • Summary

  3. Motivation SK-I m-like sub-GeV < 400 MeV m-like sub-GeV > 400 MeV m-like multi-GeV + PC m-like sub-GeV multi-ring m-like multi-GeV multi-ring Oscillation Decay Decoherence 天頂角分布

  4. Dm2L Neutrino oscillation : Pmm = 1 – sin22qsin2(1.27 ) E L m Neutrino decay : Pmm = (cos2q + sin2q x exp(– ))2 2t E L 1 Neutrino decoherence : Pmm = 1 – sin22q x (1 – exp(–g0 )) 2 E Motivation q L Path length Neutrino energy E SK-I,II の結果から neutrino decay, decoherence は否定されているが、併せる事でより否定できる。

  5. 1.5m from top & bottom 22.5kt →26.4kt 1m from barrel L/E 解析におけるイベントサンプル • データセット SK-I : 1489 days data, 100yr MC SK-II: 627 days data, 60yr MC Fully Contained (E ~1GeV) FC • Single-ring , μ-like • Multi-ring , μ-like Partially Contained (E ~10GeV) PC • OD stopping • OD through going

  6. Event summary of L/E analysis SK-I 1489 days SK-II 627 days Data MC CC nm Data MC CC nm FC single-ring multi-ring stopping through-going 1619 2105.6 (98.3%) 502 813.0 (94.2%) 114 137.0 (95.4%) 491 670.1 (99.2%) 686 876.6 (98.6%) 222 329.4 (93.6%) 51 48.5 (94.4%) 162 269.7 (99.2%) PC 2726 3725.7 Total 1121 1524.2

  7. 大気ニュートリノ L/E 振動解析 SK-I SK-II Preliminary Best fit expectation w/ systematic errors Best fit expectation w/ systematic errors Best fit result Dm2=2.4x10-3,sin22q=1.00 c2min=37.8/40 d.o.f (sin22q=1.02, c2min=37.7/40 d.o.f) Dm2=2.6x10-3,sin22q=1.00 c2min=54.8/40 d.o.f (sin22q=1.02, c2min=54.7/40 d.o.f)

  8. Constraint to neutrino oscillation parameters SK-I SK-II Preliminary 1.9x10-3 < Dm2 < 3.0x10-3 eV2 0.90 < sin22qat 90% C.L. 1.8x10-3 < Dm2 < 4.0x10-3 eV2 0.83 < sin22qat 90% C.L.

  9. Combined analysis • データセット SK-I : 1489 days data, 100yr MC SK-II: 627 days data, 60yr MC • Systematic error が SK-I,II でそれぞれ違うので別々に取り扱い、振動パラメータを共通にして振動解析を行う。 L/E binning ： 43 × 2 bin

  10. SK I+II Combined analysis results Constraint to neutrino oscillation parameters best fit result Dm2=2.4x10-3,sin22q=1.00 c2min=93.8/83 d.o.f (sin22q=1.01, c2min=92.8/83 d.o.f) 2.1x10-3 < Dm2 < 2.8x10-3 eV2 0.93 < sin22qat 90% C.L.

  11. SK-I+II combined c2distribution

  12. Summary table

  13. Dc2= c2decay-c2osc =19.5(4.4σ) Dc2 = c2decoherence-c2osc =23.3(4.8 σ) Decay Decoherence Oscillation Decay Decoherence

  14. SK-I+II 大気ニュートリノ L/E 振動解析結果 • Assuming νμ⇔ντ χ2min = 93.8/83 d.o.f at(sin22θ,Δm2)=(1.00,2.4×10-3eV2 ) • allowed region@90% C.L. 0.93<sin22θ 2.1×10-3eV2 <Δm2 < 2.8×10-3eV2 • neutrino decay,decoherence を否定。 (4σ～) • 天頂角分布解析とも一致している。

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