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Flavor identification of astronomical high energy neutrinos and the accuracy of mixing angles

SUSY 08, Seoul. Flavor identification of astronomical high energy neutrinos and the accuracy of mixing angles. Kim Siyeon Chung-Ang University 2008 - 6 - 20 Based on the work with G.R. Hwang, arXiv:0711.3122. Outline. Oscillation probability: degeneracy and uncertainty

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Flavor identification of astronomical high energy neutrinos and the accuracy of mixing angles

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  1. SUSY 08, Seoul Flavor identification of astronomical high energy neutrinos and the accuracy of mixing angles Kim Siyeon Chung-Ang University 2008 - 6 - 20 Based on the work with G.R. Hwang, arXiv:0711.3122

  2. Outline • Oscillation probability: degeneracy and uncertainty • Neutrino flux from a astronomical source • Specification of initial flux from pion decay • Neutrino telescope as ambiguity settlement • Concluding remarks K. Siyeon

  3. Oscillation • The transition probability from na to nbPab = |< nb | na (t) >|2 = dab - 4i<j∑ Re(UaiU*ajU*biUbj) sin2 xij- 2i<j∑ Im(UaiU*ajU*biUbj) sin 2xijxij = (mi2-mj2)L/4E = 1.27 Dm2L/E in unit of (eV2.km/GeV) K. Siyeon

  4. HE neutrino detection • Oscillating probability after a very long travel:P( a →b, x) = ∑|Uam|2|Ubm|2 +m  m’∑ Re(UamUam’Ubm’Ubm) cos(Dm2 x/2p) +m  m’∑ Im(UamUam’Ubm’Ubm) sin(Dm2 x/2p) Pab =∑|Uam|2|Ubm|2 • The ranges in elements estimated from PMNS at 3s CL:0.48-0.64 0.12-0.34 0.11-0.35DPab =0.33-0.53 0.30-0.41 0.33-0.47 Averaged out ! K. Siyeon

  5. pm nme nmne pmnm enmne Astronomical neutrinos • Flavor ratio: ( Fe : Fm : Ft ) • Pion source: (1:2:0) The four leptons share equally the energy of the pion. (1:1:1) at telescope • Muon damped source: (0:1:0)muon decay is suppressed due to EM energy loss. (1:1.8:1.8) at telescope • Review on atmospheric neutrinos:R(nm/ne) = 2 at low energy (En < 1GeV) R(nm/ne) -> higher and higher at high energy Kashti & Waxman 2005 Atmospheric neutrinos K. Siyeon

  6. O(km) long muon tracks τ ντ  15 m ντ km3 HE Neutrino Detection • Ice Cube: A km3-scale neutrino telescope to detect high energy, 0.1TeV < En < 10PeV. • 1 Gton effective detector mass, 4800 optical modules. K. Siyeon

  7. Initial flux identification • Assumptions:[1] Telescopes distinguish the muon-damped source from the pion source.[2] Telescopes distinguish three flavors of neutrinos near O(1015)eV, Ft(ne) : Ft(nm) : Ft(nt) .[*] Independent are three of the following four fluxes: *Ft(ne) from pion source * Ft(ne) from muon-damped source * Ft(nm) from pion source * Ft(nm) from muon-damped source K. Siyeon

  8. Flux sensitivity to mixing angles The flux of ne : • Linear and sensitive to q23 • No degeneracy with the complementary angle, cf. 1-Pmm K. Siyeon

  9. Degeneracy in probability • Probabilities and fluxes can be 8-folded degenerate at most from different sets of (q13, q23) and NH or IH. • Pme is considered together to get rid of factors of ambiguities: uncertainties or degeneracies • (a,b,c,d) for q23 < p/4(e,f,g,h) for q23 > p/4 • (a,b,e,f) for NH(c,d,g,h) for IH The JHF-Kamioka neutrino projecthep-ex/0106019 K. Siyeon

  10. p source m damped d chosen Composition of a mixed beam Type of source? • In reality, neither pure pion source nor pure muon-damped source is detected. Difficulties come from • No idea for the composition in the initial flux depending on the physical condition at astronomical bursts. • Neutrino parameters themselves bear ambiguities, broad uncertainties and degeneracies. K. Siyeon

  11. Breaking degeneracy (1) • The Dm2 is hidden in flux measurements at telescopes. • The determination of q13 is likely to indicate whether NH or IH. • If q13 >0.03, its value will be found in a few years by Double Chooz, Daya Bay, or RENO. IceCube starts running in 2013. K. Siyeon

  12. Breaking degeneracy (2) The existence of source-blind fluxes:The same magnitude of flux is obtained by a pair of initial flux from pion source and a value of q23 and a pair of initial flux from muon-damped source and p/2-q23. • In oscillation, 1-Pmm is most sensitive to q23, but is degenerate by a value of q23 andp/2- q23,, the complementary angle. • The fluxes at telescope are sensitive to q23, without giving rise to the degeneracy. K. Siyeon

  13. Concluding Remarks • The settlement of degeneracy problems by the telescope requires somewhat of improvement in precision of other experiments ahead, whose accomplishment is likely possible before 2013, the year of telescope working. • The composition of astronomical HE neutrino beams requires better precision for mixing parameters. • The determination of the neutrino parameters in different types of experiments complementary to each other. • Long-base line neutrino oscillation • Reactor neutrino oscillation • Neutrino telescope with high energy sources. K. Siyeon

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