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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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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 • Neutrino flux from a astronomical source • Specification of initial flux from pion decay • Neutrino telescope as ambiguity settlement • Concluding remarks K. Siyeon
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
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
pm nme nmne pmnm enmne 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
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
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
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
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
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
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
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
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