flavor identification of astronomical high energy neutrinos and the accuracy of mixing angles
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Flavor identification of astronomical high energy neutrinos and
the accuracy of mixing angles
Kim SiyeonChung-Ang University
2008 - 6 - 20
Based on the work with G.R. Hwang, arXiv:0711.3122
SUSY 08, Seoul
2008 – 6 – 20 SUSY08 K. Siyeon 2
Outline
I. Oscillation probability: degeneracy and uncertaintyII. Neutrino flux from a astronomical sourceIII. Specification of initial flux from pion decayIV. Neutrino telescope as ambiguity settlementV. Concluding remarks
2008 – 6 – 20 SUSY08 K. Siyeon 3
Oscillation
• The transition probability from to P = |< | (t) >|2
= i<j∑ Re(UiU*jU*
iUj) sin2 xij
i<j∑ Im(UiU*jU*
iUj) sin 2xij
xij = (mi2-mj2)L/4E = 1.27 m2L/E in unit of (eV2.km/GeV)
• Sensitive for 23
• Degenerate under 23 -> /2- 23 and under m31
2 -> - m312
• Sensitive for 13
• The leading term requires significant matter effect to distinguish the sign of m31
2 .
2008 – 6 – 20 SUSY08 K. Siyeon 4
HE neutrino detection
• Oscillating probability after a very long travel: P( →, x) = ∑|Um|2|Um|2 + m m’∑ Re(UmUm’Um’Um) cos(m2 x/2p) + m m’∑ Im(UmUm’Um’Um) sin(m2 x/2p)
P =∑|Um|2|Um|2
• The ranges in elements estimated from PMNS at 3s CL:
0.48-0.64 0.12-0.34 0.11-0.35 P =0.33-0.53 0.30-0.41 0.33-0.47
Averaged out !
2008 – 6 – 20 SUSY08 K. Siyeon 5
Astronomical neutrinos
e
e
Kashti & Waxman 2005
• Flavor ratio: ( e : )
• 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:
Re) = 2 at low energy (E < 1GeV)
R(e) -> higher and higher at high energy
Atmospheric neutrinos
e
e
2008 – 6 – 20 SUSY08 K. Siyeon 6
HE Neutrino Detection
• Ice Cube: A km3-scale neutrino telescope to detect high energy, 0.1TeV < E < 10PeV.
• 1 Gton effective detector mass, 4800 optical modules.
15 m
O(km) long muon tracks
ντ
τ ντ
kmkm33
2008 – 6 – 20 SUSY08 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, t(e) : t() : t() .
[*] Independent are three of the following four fluxes:
*t(e) from pion source * t(e) from muon-damped source* t() from pion source * t() from muon-damped source
2008 – 6 – 20 SUSY08 K. Siyeon 8
Flux sensitivity to
mixing angles
The flux of e :
• Linear and sensitive to 23
• No degeneracy with the complementary angle, cf. 1-P
2008 – 6 – 20 SUSY08 K. Siyeon 9
Degeneracy in probability• Probabilities and fluxes can be 8-folded degenerate at most from different s
ets of (13, 23) and NH or IH.
• P is considered together to get rid of factors of ambiguities: uncertainties or degeneracies
• (a,b,c,d) for 23 < /4(e,f,g,h) for 23 > /4
• (a,b,e,f) for NH(c,d,g,h) for IH
The JHF-Kamioka neutrino project
hep-ex/0106019
2008 – 6 – 20 SUSY08 K. Siyeon 10
Composition of a mixed beamType of source?• In reality, neither pure pion
source nor pure muon-damped source is detected.
Difficulties come from• No idea for the compositio
n in the initial flux depending on the physical condition at astronomical bursts.
• Neutrino parameters themselves bear ambiguities, broad uncertainties and degeneracies.
source damped
chosen
2008 – 6 – 20 SUSY08 K. Siyeon 11
Breaking degeneracy (1)
• The m2 is hidden in flux measurements at telescopes.• The determination of 13 is likely to indicate whether NH or IH.• If 13 >0.03, its value will be found in a few years by Double Chooz, Day
a Bay, or RENO. IceCube starts running in 2013.
2008 – 6 – 20 SUSY08 K. Siyeon 12
Breaking degeneracy (2)• In oscillation, 1-P is most sensitive to 23, but is degenerate
by a value of 23 and /2- 23,, the complementary angle.• The fluxes at telescope are sensitive to 23, without giving
rise to the degeneracy.
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 23 and
a pair of initial flux from muon-
damped source and /2-23.
2008 – 6 – 20 SUSY08 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.