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Neutrino oscillations: Perspectives (… for LENA?)

Neutrino oscillations: Perspectives (… for LENA?). LENA strategy meeting DESY Hamburg, Germany June 14, 2012 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Questions of interest Consequences of large q 13 discovery Worldwide picture

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Neutrino oscillations: Perspectives (… for LENA?)

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  1. Neutrino oscillations: Perspectives (… for LENA?) LENA strategy meeting DESY Hamburg, Germany June 14, 2012Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Contents • Questions of interest • Consequences of large q13 discovery • Worldwide picture • Comments on superbeam CERN-Pyhäsalmi • Sterile neutrinos (briefly) • Summary

  3. ( ) ( ) ( ) = x x Three flavor mixing • Use same parameterization as for CKM matrix Pontecorvo-Maki-Nakagawa-Sakata matrix Potential CP violation ~ q13 (sij = sin qij cij = cos qij)

  4. Why is dCP interesting? sind • CP violationNecessary condition for successful baryogenesis (dynamical mechanism to create matter-antimatter asymmetry of the universe) thermal leptogensis by decay of heavy see-saw partner? • Model buildinge.g. TBM sum rule: q12 = 35 + q13cosd (Antusch, King) • Need performance which is equally good for all dCP cosd Correction leadingto non-zero q13? Symmetrye.g. TBM, BM, …?

  5. Mass spectrum/hierarchy • Specific models typically come together with specific MH prediction • Good model discriminator (Albright, Chen, hep-ph/0608137) 8 8 Normal Inverted

  6. q13 discovery 2012 • First evidence from T2K, Double Chooz • Discovery (~ 5s) independently (?)by Daya Bay, RENO Daya Bay 3s 1s error bars (from arXiv:1204.1249)

  7. Neutrino oscillations: Summary • Three flavors: 6 params(3 angles, one phase; 2 x Dm2) • Describes solar and atmospheric neutrino anomalies, as well as reactor antineutrino disapp.! Solaroscillations:Amplitude:q12Frequency: Dm212 Atmosphericoscillations:Amplitude:q23Frequency: Dm312 Coupling: q13 (Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002;Daya Bay, RENO 2012) Suppressed effect: dCP

  8. Consequences of large q13 • q13 well measured by Daya Bay • MH/CPV difficultNeed new facility! Huber, Lindner, Schwetz, Winter, 2009

  9. Mass hierarchy measurement? • Mass hierarchy [sgn(Dm2)] discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU?, LENA?, …) Barger et al, arXiv:1203.6012;IH more challenging Perhaps differentfacilities for MH and CPVproposed/discussed? • NB: basically any long-baseline experiment at design luminosity with E > 1 GeV and L >> 1000 km can for all dCP measure the hierarchy by sufficient Earth matter effects (MSW effect)!

  10. Long-baseline neutrino sources There are three possibilities to artificially produce neutrinos: • Beta decay: • Example: Nuclear reactors, Beta beams • Pion decay: • From accelerators: • Muon decay: • Muons produced by pion decays! Neutrino Factory Superbeam Muons,neutrinos Pions Neutrinos Protons Target Selection,focusing Decaytunnel Absorber

  11. The new paradigm: Precision? C2P = LBNO:CERN-PyhäsalmiL~2300 km, 100kt liquid argon • CP violation performance represents only two possible values of dCP (0 and p) • Need new performance indicators • Reveal that some experiments (narrow beam spectra!) strongly optimized for CPV Bands: q13 allowed ranges 1s (Coloma, Donini, Fernandez-Martinez, Hernandez, 2012; concept: WW, PRD 70 (2004) 033006 )

  12. The big unknown: Systematics • Systematics important for large q13 • New treatment needed • Use explicit near-far detector simulations • Use same knowledge for cross sections for all experiments • Use same assumptions for systematics implementation! (Huber, Mezzetto, Schwetz, 2007) (Coloma, Huber, Kopp, Winter, in preparation)

  13. Systematics: Values? Educated guessof param. range Same parameters for all superbeams:LBNE, LBNO, …Same assumptions for X-sections (Coloma, Huber, Kopp, Winter, in preparation)

  14. New performance indicator (Coloma, Huber, Kopp, Winter, in preparation)

  15. Precision: Worldwide comparison (bands: systematics opt.-cons. includesmatter densityuncertainty 1% - 5%) CKM phase PRELIMINARY Most robust wrt systematics? (Coloma, Huber, Kopp, Winter, in preparation)

  16. Superbeam CERN-Pyhäsalmi L ~ 2300 km • Main impact factors: • Neutral current backgrounds versus efficiency • Fiducial volume (cost?) • Background migration(no migration matrices yet: NC backgrounds reconstructed in energy window of signal) 50 kt LENA90% eff.10% NC 100 kt liquid argon 50 kt LENA90% eff.30% NC PRELIMINARY (special thanks: Pilar Coloma)

  17. Evidence for sterile neutrinos? • LSND/MiniBooNE • Reactor+gallium anomalies • Global fits (MiniBooNE @ Neutrino 2012) (B. Fleming, TAUP 2011) (Kopp, Maltoni, Schwetz, 1103.4570)

  18. Example: 3+1 framework • Well known tension between appearance and disapp. data (appearance  disapp. in both channels) • Need one or more new experiments which can test • ne disappearance (Gallium, reactor anomalies) • nm disappearance (overconstrains 3+N frameworks) • ne-nm oscillations (LSND, MiniBooNE) • Neutrinos and antineutrinos separately (CP violation? Gallium vs reactor?) • Example: nuSTORM - Neutrinos from STORed Muons(LOI: arXiv:1206.0294) LENA: see C. Hagner‘s talk!Summary of options: Appendix of white paper arXiv:1204.5379

  19. Summary: Perspectives for LENA? • LENA interesting recipient for a superbeam[possibly beta beam, dep. on location] • Robust wrt systematical errors for CERN-Pyhäsalmi • Robust on beam side? [0.8 MW vs. 4 MW] • Similar performance for all values of dCP • Mass hierarchy measurement certainly possible • Comparison to alternatives (e.g. liquid argon) depends on • Fiducial mass for same budget? • Neutral current BGs versus efficiency • Event migration (status?) • Yet to little information for conclusive statements?

  20. BACKUP

  21. CERN-LENA: def. systematics • Fiducial mass/ efficiency more important than backgrounds 100 kt liquid argon 100 kt LENA90% eff.10% NC 50 ktLENA90% eff.30% NC PRELIMINARY 50 kt LENA90% eff.10% NC 50 ktLENA50% eff.10% NC (special thanks: Pilar Coloma)

  22. Impact of near detector (defaultsystematics) PRELIMINARY (Coloma, Huber, Kopp, Winter, in preparation)

  23. Comparison to eff. syst. PRELIMINARY (Coloma, Huber, Kopp, Winter, in preparation)

  24. Systematics impact PRELIMINARY (Coloma, Huber, Kopp, Winter, in preparation)

  25. Summary of options (from: Coloma, Donini, Fernandez-Martinez, Hernandez, 2012)

  26. Beams: Appearance channels (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004) • Antineutrinos: • Magic baseline:L~ 7500 km: Clean measurement of q13 (and mass hierarchy) for any energy, value of oscillation parameters!(Huber, Winter, 2003; Smirnov 2006)In combination with shorter baseline, a wide range of very long baseline will do! (Gandhi, Winter, 2006; Kopp, Ota, Winter, 2008)

  27. 90% CL, existing equipment 3s, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan Mass hierarchy discovery? Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44

  28. Matter effect (MSW) (Wolfenstein, 1978; Mikheyev, Smirnov, 1985) • Ordinary matter: electrons, but no m, t • Coherent forward scattering in matter: Net effect on electron flavor • Hamiltonian in matter (matrix form, flavor space): Y: electron fraction ~ 0.5 (electrons per nucleon)

  29. Parameter mapping • Oscillation probabilities invacuum:matter: Matter resonance: In this case: - Effective mixing maximal- Effective osc. frequency minimal For nm appearance, Dm312:- r ~ 4.7 g/cm3 (Earth’s mantle): Eres ~ 6.4 GeV- r ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 2.8 GeV  MH Resonance energy:

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