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Probing neutrino flavor transition mechanism with ultrahigh energy astrophysical neutrinos

Probing neutrino flavor transition mechanism with ultrahigh energy astrophysical neutrinos. 賴光昶 長庚大學通識中心. 2014 海峡两岸粒子物理与宇宙学研讨会 黃山，安徽， May 9th, 2014. KCL, T.-C. Liu and G.-L. Lin, PRD 82, 103003 KCL, T.-C. Liu and G.-L. Lin, PRD 89, 033002. Astrophysical neutrino Neutrino flavor transition

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Probing neutrino flavor transition mechanism with ultrahigh energy astrophysical neutrinos

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  1. Probing neutrino flavor transition mechanism with ultrahigh energy astrophysical neutrinos • 賴光昶 • 長庚大學通識中心 2014海峡两岸粒子物理与宇宙学研讨会 黃山，安徽，May 9th, 2014 KCL, T.-C. Liu and G.-L. Lin, PRD 82, 103003 KCL, T.-C. Liu and G.-L. Lin, PRD 89, 033002

  2. Astrophysical neutrino • Neutrino flavor transition • Neutrino signals in neutrino telescopes • Test of transition models

  3. Ernie

  4. Bert, 1.04PeV Ernie, 1.14PeV

  5. Astrophysical neutrino “Astrophysical” means

  6. Flavor transition • Q-representation • Standard oscillation • Neutrino decay • Quantum decoherence • Pseudo-Dirac neutrino

  7. Q-representation Tri-bimaximal matrix, eigenvectors of TBM: neutrino on Earth→φ=Pφ0←neutrino at the source φ0=(φ0(νe), φ0(νμ), φ0(ντ))=1/3V1+aV2+bV3 φ=ϰV1+ϱV2+λV3 (ϰ, ϱ, λ)T=Q(1/3, a, b)T ⇒Q≡A-1PA

  8. Q-representation

  9. Standard oscillation

  10. Neutrino decay Normal hierarchy Inverted hierarchy

  11. Neutrino decay • The heaviest and middle states decay into the lightest one(j=1 or 3).-dec1 • The heaviest state decays into the middle and lightest ones.-dec2 { ε1=cos2ϑ23-(√2/3)sinϑ13, ε2=(1/2)cos2ϑ23-ε1

  12. Quantum decoherence • distance dependent • γ→0 or d→∞, Qdc=Qosc

  13. Pseudo-Dirac neutrino • ∆mi2: the mass-squared difference between active and sterile states. ∆mi2 =∆m2 In the limit of L(z)/4Eν≫1/∆mi2, Qpd=1/2 Qosc

  14. Neutrino events 125m corresponds to the decay length of a 2.5 PeV tau lepton.-dist. between strings ≈1km corresponds to the decay length of a 25 PeV tau lepton.-size of IceCube 1054.5154

  15. Observables RI: track-to-shower ratio; RII:shower-to-track ratio

  16. Observables • ϕ0=(ϕ(νe), ϕ(νμ), ϕ(ντ))=1/3 V1+aV2+bV3. • for non-ντ sources, a=-1/3+b and let RII≡R. • flux conservation assumed • For pion and damped-muon sources

  17. Statistical analysis • We consider: • i=π, only pion source • i=π and µ, both pion and damped-muon source • σ=10% assumed G. Fogli, et al., PRD 86, 013012

  18. Statistical analysis • Legend: • ✕: oscillation • ▵: dec1-n, ▴:dec1-i • ￮, ◇, ⃞: dec2-n • •, ◆, ▪: dec2-i

  19. 1σ region 3σ region Pion source

  20. 1σ region 3σ region Pion source

  21. 1σ region 3σ region Pion source

  22. 1σ region 3σ region Pion and Muon sources

  23. 1σ region 3σ region Pion and Muon sources

  24. 1σ region 3σ region Pion and Muon sources

  25. Summary • Neutrino astronomy has begun. • 28 astrophysical events observed • Flavor transitions can be probed: • Q-representation • Observable defined • 𝜒2-analysis performed

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