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Proton decay studies in Liquid Argon TPC

Proton decay studies in Liquid Argon TPC. Dorota Stefan Epiphany Conference on Neutrinos and Dark Matter 5 - 8 January 2006, Cracow, Poland. References. L. E. Ibanez, CERN-TH.5237/88 Hitoshi Murayama and Aaron Pierce, Phys. Rev. D.65.055009(2002)

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Proton decay studies in Liquid Argon TPC

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  1. Proton decay studies in Liquid Argon TPC Dorota Stefan Epiphany Conference on Neutrinos and Dark Matter 5 - 8 January 2006, Cracow, Poland

  2. References • 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)

  3. The outline of the presentation • Grand Unification Theory • Results from SuperKamiokande and Soudan 2 • Simulation studies of proton decay in LAr TPC

  4. The 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

  5. SU(5) SO(10) E6 GUT • SU(5) • unification scale ~ 1015 GeV • 24 gauge bosons • no place for more quarks or leptons SO(10) • E6 • plenty of possibilities for breaking the symmetry down to the standard model • extra particles

  6. SUSY GUTs • SUSY • each SM particle has its super-partner • SM bosons  super-fermions • SM fermions  super-bosons

  7. Search 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 Result from SK has been reached ~ 1033 predicted by SU(5): t/B ~ 1031+1year Result from SK has been reached ~ 1032 t/B(p nK+)  2.9 x 1030

  8. Search for pe+p0in SuperKamiokande Signature for p  e+p0 in the SK detector Limit from PDG July 2004 t (p  e+p0) > 5.0 x 1033 years (79.3 ktyr exposure)

  9. Search for pK+n in SuperKamiokande K+ p+ p0 K+ m+ nm For a bound proton -prompt gamma-ray For a free proton -mono-energetic muon p  K+n Limits from PDG July 2004 t (p  K+n) > 1.6 x 1033 years The newest result: t (p  K+n) > 2.3 x 1033 years

  10. Search for pK+n in experiment Soudan 2 Simulated events K+ p+ p0 p0 K+ p+ K+ m+ nm e+ K+ m+ (236MeV/c)

  11. Proton decay in ICARUS detector

  12. Different channels for proton decay in LAr high efficiency low bakground relevant results in relatively short time

  13. Analysis of the particle which stops in LAr Kaon Energy Loss of the detected particle from the last wire to the last minus last wire Pion

  14. Particle Identification by using Neural Network Signal and background distribution The geometry of the Neural Network used for particle recognition: Kaon Pion 9 : 3 : 3

  15. Purity - Efficiency for kaon and pion Kaon • Electronics noise is not taken into account • particles are very well recognized by the neural network with very high efficiency and purity Pion purity = 100% Nsig (OutputSet)/ ( Nbkg(OutputSet) + Nsig(OutputSet) ) efficiency = 100% Nsig (OutputSet) / Nsig(InputSet)

  16. Summary • 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 n decay ...if SUSY GUTs are correct, nucleon decay must be seen soon PDG

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