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TeV Particle Astrophysics, 24-28 September, 2008, Beijing, China. Shun Zhou. IHEP, CAS, Beijing. Based on our recent works: Z.Z. Xing and S. Zhou, PLB (2008); PRD (2006). Outline. UHE Neutrinos: Challenges and Opportunities Determination of the Initial Flavor Composition
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IHEP, CAS, Beijing
Based on our recent works: Z.Z. Xing and S. Zhou, PLB (2008); PRD (2006).
Probing Neutrino Mixing and Unitarity ViolationatNeutrino Telescopes
“Grand Unified” Neutrino Spectrum
-Standard Solar Model
Flux of Cosmic Rays
Pierre Auger, PRL, 08
HiRes, PRL, 08
Observation of GZK cutoff ?
Existence of UHE Neutrinos?
Neutrino Telescope: AMANDA
km3-scale NT: IceCube
South Pole, Antarctica
by magnetic field
To explore extremely high energy region
To locate distant astrophysical sources
To study new scenarios in particle physics
Conventional source:decays of charged ’s produced from UHEp +p or p +collisions.
Naïve expectation:ultra-long-baseline UHE cosmic -oscillations (Learned, Pakvasa 95).
■ Learned, Pakvasa, APP (95)
★ Athar et al, PRD (00)
★ Bento et al, PLB (00)
★ Gounaris, Moultaka, hep-ph/0212110
★ Barenboim, Quigg, PRD (03)
★ Beacom et al, PRD (03)
★ Keraenen et al, PLB (03)
★ Beacom et al, PRD (04)
★ Hooper et al, PLB (05)
★ Serpico, Kachelriess, PRL (05)
★ Bhattacharjee, Gupta, hep-ph/0501191
★ Serpico, PRD (06)
★ Xing, PRD (06)
★ Xing, Zhou, PRD (06)
★ Winter, PRD (06)
★ Athar et al, MPLA (06)
General sources and contaminations
(Parametrization, Xing & Zhou 06)
active-sterile neutrino mixing & oscillation
★ Rodejohann, JCAP (07)
★ Majumdar, Ghosal, PRD (07)
★ Xing, NPB (Proc. Suppl.) (07)
★ Blum, Nir, Waxman, arXiv:0706.2070
★ Lipari et al, PRD (07)
★ Meloni, Ohlsson, PRD (07)
★ Awasthi, Choubey, PRD (07)
★ Hwang, Kim, arXiv:0711.3122
★ Xing, NPB (Proc. Suppl.) (08)
★ Pakvasa et al, JHEP (08)
★ Choubey, Niro, Rodejohann, PRD (08)
★ Maltoni, Winter, JEHP (08)
★ Xing, Zhou, PLB (08)
- symmetry breaking effects and CP phase
Test of CPT, Q-coherence, unitarity, …
Can -telescopes (IceCube, KM3NeT) do …?
The transitional probability
with unitary mixing matrix
The typical distance for AGN: L~100 Mpc, while the oscillation length
After many oscillations, the averaged transition probabilities given as
The oscillatory terms disappear, also applicable to anti-neutrino oscillations
’s are generated from ppor pcollisions. UHE ’s produced from the decays of ’s and the secondary ’s.
UHE neutrinos are produced from the beta decay of neutrons.
Source is optically thick to ’s, not to ’s, different lifetimes.
With the initial neutrino fluxes, the fluxes at the neutrino telescope:
Parametrization[Xing, Zhou, Phys. Rev. D 74, 013010 (2006)]:
where characterizes the small amount of tau ’s at the source [e.g., from Ds- or B-meson decays (Learned, Pakvasa 1995)].
Dominant contribution of charm at EHE:
[Enberg, Reno, Sarcevic, arXiv:0808.2807[hep-ph]
Determination of the source parameters
Define the working observables:
Only two independent:
Question:Is it possible to determine the flavor distribution at sources?
A global analysis of neutrino oscillation data: [Strumia &Vissani, 2006]
Transition Probabilities [Xing, Zhou, PRD, 06]
Large uncertainties from oscillation data: mixing angles and Dirac CP phase
Q:What are the sufficient and necessary conditions for flavor democracy?
Given the conventional source
A:The unique parametrization-independent conditions [Xing, Zhou, 08]
In the standard parametrization:
To measure the neutrino mixing parameters at neutrino telescopes
Minimal Unitarity Violation(Antusch et al 07):
-Only 3 light neutrino species are considered;
-Sources of non-unitarity only in the SM Lagrangian which involves neutrinos.
e.g., TeV Seesaw Models:
Heavy Majorana fermions
Neutrino mixing matrix is NON-unitary invarious neutrino mass models
Constraints from experimental data: neutrino oscillations, W&Z decays, rare lepton-flavor-violating decays, lepton universality tests, ……
Full parameterization of 3x3 non-unitary matrix: [Xing, PLB, 2008]
A:~ Identity matrix
Non-unitary deviation from TB Mixing: [Xing, Zhou, PLB, 08; Luo, PRD, 08]
The non-unitary neutrino mixing matrix with additional 6 angles&6 phases
The flavor distribution of neutrino fluxes at the detectors reads
si4 ≤ 0.1
s14 s24 ≤ 7.0 x10-5
Free relative phase
The total flux of cosmic neutrinos is not conserved
Observable? Calibration by the flux of TeV photons
1. Neutrinos from the Sun and Supernova explosion have been observed, and have greatly improved our understanding of the stellar evolution and the properties of themselves. High energy neutrinos from other cosmic sources are promising to be discovered.
2. If neutrino mixing parameters are precisely measured in the terrestrial neutrino experiments, the flavor composition of cosmic neutrinos at the sources can be determined. It may help us locate the cosmic accelerators and learn more about the astrophysical processes at the sources.
3. On the other hand, if the sources are well known, UHE neutrinos may help us understand their intrinsic properties and test various scenarios of physics beyond the standard model.
4. The new generation of neutrino telescopes may serve as a powerful tool for us to go further both in astrophysics and particle physics.