Proton decay studies in Liquid Argon TPC
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Proton decay studies in
Liquid Argon TPC
Dorota StefanEpiphany Conference on Neutrinos and Dark Matter
5 - 8 January 2006, Cracow, Poland
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ReferencesReferences
• L. E. Ibanez, CERN-TH.5237/88• Hitoshi Murayama and Aaron Pierce, Phys. Rev. D.65.055009(2002)• Mario E. Gómez Yukawa coupling and proton decay in SUSY models• K. Kobayashi, hep-ex/0502026• Y. Hayato, hep-ex/9904020• Kenneth S. Ganezer, the SuperKamiokande Collaboration, The Search for Proton Decay at SuperKamiokande • W.W.M. Allison, hep-ex/9803030• D. Wall, hep-ex/9910026• The ICARUS Collaboration, ICARUS TM 05-XX(2005)
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The outline of the presentationThe outline of the presentation
• Grand Unification Theory
• Results from SuperKamiokande and Soudan 2
• Simulation studies of proton decay in LAr TPC
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The Grand Unification IdeaThe Grand Unification Idea
• Three U(1)SU(2)SU(3) interactions into a single one
• There are different candidates of the unification group such as SU(6) ... SU(N+1) or SO(10) ... SO(2N+4)
• The most attractive groups are SO(10) and E6
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SU(5) SO(10) ESU(5) SO(10) E66 GUT GUT
SU(5)SU(5)• unification scale ~ 1015
GeV• 24 gauge bosons
• no place for more quarks or leptons
• extra particles
EE66
• plenty of possibilities for breaking the symmetry down to the standard model
SO(10)SO(10)
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SUSY GUTsSUSY GUTs
SUSYSUSYeach SM particle has its super-partner
• SM bosons super-fermions• SM fermions super-bosons
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Search for proton decaySearch for proton decay
• Experiment SuperKamiokande with water Cherenkov detector -Minimal SU(5) was ruled out by SK
-Minimal SU(5) SUSY:
• SUSY GUT models have been tested in SuperKamiokande and Soudan 2 experiments
predicted by SU(5):year
p K+) 2.9 x 1030
Result from SK has been reached ~ 1033
Result from SK has been reached ~ 1032
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Search forSearch for p pee++in SuperKamiokandein SuperKamiokande
Limit from PDG July 2004Limit from PDG July 2004
p p e ex 10x 1033 33 years (79.3 ktyr exposure)years (79.3 ktyr exposure)
Signature for p Signature for p ee++ in the SK detectorin the SK detector
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Search forSearch for p pKK++in SuperKamiokandein SuperKamiokande
K+
K+
For a bound protonFor a bound proton -prompt gamma-ray
For a free protonFor a free proton -mono-energetic muon
Limits from PDG July 2004Limits from PDG July 2004
p Kx 1033 years
The newest result:
p Kx 1033 years
p p K K
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Search forSearch for p pKK++in experiment Soudan 2in experiment Soudan 2
K+
MeV/c
e+
K+
Simulated eventsSimulated events
K+
K+
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Proton decay in ICARUS detectorProton decay in ICARUS detector
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Channel
Efficiency (%)
Background (5 kTonxyear)
B x 1030years (5 kTonxyear)
PDG limit x1030
years
Needed Exposure to reach PDG (kTon x year)
p K+ p K+
p e+
p p
96.75
97.55
18.60
41.85
44.80
0.005
0.005
0.125
3.91
0.04
565
570
109
117
262
2300
245
82
25
473
20.36
2.15
3.78
0.52
9.04
Different channels for proton decay in LArDifferent channels for proton decay in LAr
high efficiency low bakground relevant results in relatively short time
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Analysis of the particle which stops in LAr Analysis of the particle which stops in LAr
Kaon
Pion
Energy Loss of the detected particle from the last wire to the last minus last wire
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Particle Identification by using Neural NetworkParticle Identification by using Neural Network
Kaon
Pion
Signal and background distribution
The geometry of the Neural Network used for particle recognition:
9 : 3 : 3
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Purity - Efficiency for kaon and pionPurity - Efficiency for kaon and pion
purity = 100% Nsig (OutputSet)/ ( Nbkg(OutputSet) + Nsig(OutputSet) )
efficiency = 100% Nsig (OutputSet) / Nsig(InputSet)
Kaon
Pion
- Electronics noise is not taken into account
- particles are very well recognized by the neural network with very high efficiency and purity
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SummarySummary
• Variety of GUT models to be tested experimentally – proton decay essential in model verification
• SuperKamiokande has given impressive limits and excluded minimal SU(5)
• Sufficiently large Liquid Argon detector ideal for background-free studies of the p K decay
...if SUSY GUTs are correct, nucleon decay must be seen soonPDG