Neutrino telescopes and possible solutions to ambiguities in neutrinos Yong Pyong 2008 APCTP Workshop Neutrino telescopes and possible solutions to ambiguities in neutrinos Kim Siyeon Chung-Ang University 2008 - 2 - 26

Contents Degenerate probability of oscillation 3 - 5 Astrophysical neutrinos 6 - 7 High energy neutrino detection 8 - 10 Neutrino ambiguity settlement 11 - 16 Concluding remarks 17 KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Degenerate probability (1) Neutrino Oscillation: The transition probability from na to nb Pab = |< nb | na (t) >|2 = dab - 4 i<j∑ Re(UaiU*ajU*biUbj) sin2 xij - 2 i<j∑ Im(UaiU*ajU*biUbj) sin 2xij xij = (mi2-mj2)L/4E = 1.27 Dm2L/E in unit of (eV2.km/GeV) Actual measurements: Ambiguities: uncertainties and degeneracies ∫dEn dF/dEn sCC(En) Pab(En) e(En) ∫dEn dF/dEn sCC(En) e(En) <Pab>= KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Degenerate probability (2) Ambiguities: Either uncertainty or degeneracy ? Degeneracy: Too many parameters but not that many experimental data Physical parameters: me, mm, mt, m1, m2, m3 , q12, q23, q13, d. Probabilities are degenerate due to: sign(Dm312), sign(q23-p/4), pairs of (q13 , d). KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Degenerate probability (3) Disappearance probability: degenerate under changes q23 -> p/2-q23 Dm231 -> -Dm231 normal hierarchy Inverted hierarchy Appearance probability: sign(Dm231)sin2q13cosd is degenerate under multiple combinations Pairs of (q13, d) consist 8-fold degeneracy. KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Astronomical neutrinos (1) UHECR observation ! GRB models : A relativistic jet breaks through the stellar envelope 100TeV (or higher) neutrino sources, c.f., choked jets can produce TeV neutrino burst. pg -> D+ -> pp+ dominant in GRB, producing HE neutrinos below the threshold. pp -> p+-,K +- dominant in low energy. Typical energy of neutrinos from pion(20%) decay is 5% of protons. KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Astronomical neutrinos (2) Flavor ratio: ( Fe : Fm : Ft ) Pion source: (1:2:0) ~ (p+ → … → e++nm+nebar+nmbar). The four leptons share equally the energy of the pion. (1:1:1) at telescope Muon damped source: (0:1:0) from pion decays with muon absorption. dN/dE ~E-2, e.g., from GRB, above O(PeV). (1:1.8:1.8) at telescope pmnm enmne pm nm e nmne Kashti & Waxman 2005 KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

HE neutrino detection (1) 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) = dab - 2 m<m’∑ Re(UamUam’Ubm’Ubm) Neutrino fluxes are normalized s.t. F(ne)+F(nm)+F(nt)=1 Detected fluxes at telescope are F(na)=1/3(Pae+2Pam) for pion source. F(na)=Pam for muon-damped source. Averaged out ! KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

HE Neutrino Detection (2) Ice Cube: A km3-scale neutrino telescope to detect high energy, 0.1TeV < En < 10PeV. 1 Gton effective detector mass, 4800 optical modules.  15 m O(km) long muon tracks KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

HE Neutrino Detection (3) Measurement of neutrino flux: IceCube will distinguish nm, ne, nt based on the event characteristics: nm → m produce long muon tracks Good angular resolution, but limited energy resolution ne → e produce EM showers Good energy resolution, poor angular momentum nt → t → nt produce ‘double-bang’ events at high energy. One shower when t is produced, another when it decays. ντ τ km3 KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Neutrino ambiguity settlement (1) - Hwang and Siyeon arXiv:0711 Neutrino ambiguity settlement (1) - Hwang and Siyeon arXiv:0711.3122, submitted to PRD Assumptions: [1] Telescopes distinguish the muon-damped source from the pion source. [2] Telescopes distinguish three flavors of neutrinos near O(1015)eV, independently. Kashti and Waxman KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Neutrino ambiguity settlement (2) Probabilities and fluxes can be 8-folded degenerate at most from different sets of (q13, q23) and NH or IH. Physical values are common in all figures. In principle, the detection at tele- scope can solve all the degeneracy problems. The JHF-Kamioka neutrino project hep-ex/0106019 KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Neutrino ambiguity settlement (3) The Dm2 is hidden in flux measurements at telescopes. The determination of q13 is likely to direct indication of mass spectrum, NH or IH. KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Neutrino ambiguity settlement (4) In oscillation, 1-Pmm is most sensitive to q23, but is degenerate by a value of q23 and p/2- q23,, the complementary angle. The fluxes at telescope are sensitive to q23, without giving rise to the degeneracy. KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Neutrino ambiguity settlement (5) 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. KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

Neutrino ambiguity settlement (6) Safe distinction between different types of initial fluxes require better precisions in mixing angles, which can be obtained at coming stage of LBL and Reactor oscillations. KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP

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 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. Neutrino astronomy ! - Direct messenger of astronomical events. (better than protons) - Background-free detection. KS… 2008 - 2 - 26 Yong Pyong 2008 APCTP