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Perspectives for neutrino oscillations .

Perspectives for neutrino oscillations . Walter Winter DESY, 10./18.06.2014. Contents. Introduction to neutrino oscillations Current knowledge of neutrino oscillations The future: M easurement of d CP Determination of the neutrino mass ordering Summary and conclusions.

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Perspectives for neutrino oscillations .

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  1. Perspectives for neutrino oscillations. Walter Winter DESY, 10./18.06.2014

  2. Contents • Introduction to neutrino oscillations • Current knowledge of neutrino oscillations • The future: • Measurement of dCP • Determination of the neutrino mass ordering • Summary and conclusions

  3. Introduction to neutrino oscillations

  4. Neutrinos from the atmosphere • The rate of neutrinos should be the same from below and above • But: About 50% missing from below • Neutrino change their flavor on the path from production to detection: Neutrino oscillations • Neutrinos are massive!(Super-Kamiokande: “Evidence for oscillations of atmospheric neutrinos”, 1998)

  5. Neutrino production/detection • Neutrinos are only produced and detected by the weak interaction: • The dilemma: One cannot assign a mass to the flavor states ne, nm, nt! Interaction with SU(2) symmetrypartner only Electron  electron neutrino neMuon  muon neutrino nmTau  Tau neutrino nt e, m, t ne, nm, nt W exchange particle(interaction) Production asflavor state

  6. Which mass do the neutrinos have? • Thereis a setofneutrinosn1, n2, n3, forwhich a masscanbeassigned. • Mixtureofflavorstates: • Not unusual, knowfromthe Standard Model forquarks • However, themixingsoftheneutrinosaremuch larger! sin22q13=0.1, d=p/2

  7. Neutrino oscillation probability Standard derivation N active, S sterile (not weaklyinteracting) flavors • Mixing offlavorstates • Time evolutionofmassstate • Transition amplitude • Transition probability “quarticre-phasing invariant“

  8. Further simplifications • Ultrarelativistic approximations:L: baseline (distance source-detector) • Plus some manipulations: “Master formula“ “mass squared difference“F(L,E)=L/E “spectral dependence“ • For antineutrinos: U  U*

  9. Two flavor limit: N=2, S=0 • Only two parameters: • From the master formula:Disappearance or survival probabilityAppearance probability Lower limit for neutrino mass!

  10. ( ) ( ) ( ) = x x Three flavors: Mixings • Use same parameterization as for CKM matrix Pontecorvo-Maki-Nakagawa-Sakata matrix • Neutrinos  Anti-neutrinos: U  U* (neutrino oscillations) • If neutrinos are their own anti-particles (Majorana neutrinos): U  U diag(1,eia,eib) - do enter 0nbb, but not neutrino oscillations Potential CP violation ~ q13 (sij = sin qij cij = cos qij)

  11. Three active flavors: Masses • Two independent mass squared splittings, typically (solar) (atmospheric)Will be relevant for neutrino oscillations! • The third is given by • The (atmospheric) mass ordering (hierarchy) is unknown (normal or inverted) • The absolute neutrino massscale is unknown (< eV) 8 8 Normal Inverted

  12. Current knowledge of neutrino oscillations

  13. Three flavors: Simplified • What we know (qualitatively): • Hierarchy of mass splittings • Two mixing angles large, one (q13) small ~ 0? • From the “master formula“, we have

  14. Two flavor limits Two flavor limits by selection of frequency: • Atmospheric frequency: D31 ~ p/2 D21 << 1 • Solar frequency: D21 ~ p/2 D31 >> 1 averagesout Select sensitive termby choice of L/E! 0.5

  15. Atmospheric neutrinos Super-Kamiokande From and q13 small we have: Pee ~ 1, Pem ~ Pme ~ 0 and  Two flavor limit with particular parameters q23, Measuresne, nm

  16. Reactor neutrinos • In the presence of q13: atmospheric solar K. Heeger New idea: Identical detectors, L ~ 1-2 kmto control systematics(Minakata, Sugiyama, Yasuda, Inoue, Suekane, 2003; Huber, Lindner, Schwetz, Winter, 2003) Chooz Double Chooz Daya BayRENO KamLAND

  17. (short distance) (also: T2K, Double Chooz, RENO)

  18. Three flavors: Summary • Three flavors: 6 params (3 angles, one phase; 2 x Dm2) • Describes solar and atmospheric neutrino anomalies, as well as reactor antineutrino disappearance! Solaroscillations:Amplitude:q12Frequency: Dm212 Atmosphericoscillations:Amplitude:q23Frequency: Dm312 Coupling: q13 (Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002;Daya Bay, RENO 2012; MINOS, T2K …) Suppressed effect: dCP

  19. Precision of parameters? ± 2% ± 4% (or better) ± 4% ± 3% ± 3% Age of theprecision flavor physicsof the lepton sector Open issues:- Degeneracies (mass ordering, octant)- CP phase Gonzalez-Garcia, Maltoni, Salvado, Schwetz, JHEP 1212 (2012) 123

  20. Current status and perspectives for existing equipment • Indication for dCP, no evidence for mass hierarchy • Potential of existing equipment Capozzi, Fogli, Lisi, Marrone, Montanino, Palazzo, arXiv:1312.2878 Main difference: NOvA data! T2K, NOvA, Double Chooz, Daya Bay; 5 years each CP cons. High CL determinationrequires new equipment NH simulated IH simulated Huber, Lindner, Schwetz, Winter, JHEP 0911 (2009) 044

  21. Largest, bi-annual conference of the neutrino community, 550 participants • Highlights: • Discovery of cosmic neutrinos, by IceCube • First direct high-CL evidence for nm to ne flavor transitions, by T2K • First atmospheric measurement of leading atmospheric parameters comparable withlong-baseline experiments, by IceCube-DeepCore(analysis done by DESY-Zeuthen group) • q13 central value shifts down (Daya Bay), tensionwith T2K increased; may strengthen hint for maximal leptonic CP violation dCP~-p/2 • P5 prioritisation of Long Baseline Neutrino Oscillation Experiment at Fermilab • DESY with three plenary talks one of the strongest represented institutions in the program (after INFN, before Fermilab) • Juan-Pablo Yanez @ Neutrino 2014

  22. The future: measurement of dCP

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

  24. Necessary conditions for the observation of CP violation • Since  need spectral info! • Since for a=b need to observe flavor transitions • Need (at least) three flavors(actually conclusion in quark sector by Kobayashi, Maskawa, Nobel Prize 2008) No CP violation in two flavor subspaces! Need to be sensitive to (at least) two mass squared splittings at the same time! ~ Jarlskog invariant

  25. Electron-muon neutrino flavor transitions • Antineutrinos: • Silver: • Platinum, T-inv.: (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004)

  26. Possible experimental setups (future) + Daya Bay (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  27. Performance • Comparison at default systematics: ~ LBNE/LBNO (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  28. Example: Neutrino FactoryInternational Design Study (IDS-NF) • IDS-NF: Initiative from ~ 2007-2014 to present a design report, schedule, cost estimate, risk assessment for a neutrino factory (Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000) Signal prop. sin22q13 Contamination  magnetized detector! Muons decay in straight sections of a storage ring

  29. Steve Geer‘s vision Paul Soler

  30. Systematics: Main challenges for dCP Robust wrt systematics Main impact:Matter density uncertainty Neutrino Factory Operate in statistics-limited regimeExposure more important than near detector High-E superbeam(e. g. LBNE) QE ne X-sec critical:cannot be measured in near detectorTheory: ne/nm ratio?Experiment: Low-E (QE!) superbeam (Coloma, Huber, Kopp, Winter, arXiv:1209.5973)

  31. Mass hierarchy determination

  32. Why would one like to measure the mass ordering? • Specific models typically come together with specific MH prediction (e.g. textures are very different) • Good model discriminator (Albright, Chen, hep-ph/0608137) 8 8 Normal Inverted

  33. Method 1: Matter effects in neutrino oscillations • Ordinary matter: electrons, but no m, t • Coherent forward scattering in matter: Net effect on electron flavor • Hamiltonian in matter (matrix form, flavor space): (Wolfenstein, 1978; Mikheyev, Smirnov, 1985) Y: electron fraction ~ 0.5 (electrons per nucleon)

  34. Parameter mapping … for two flavors, constant matter density • Oscillation probabilities invacuum: matter: • Enhancement condition 8 8 InvertedDm312 <0 NormalDm312 >0

  35. Long baseline experiments(up to first vacuum osc. maximum) Best-fit valuesfrom arXiv:1312.2878(first octant) L=1300 km Matter effect ~ sin22q13 sin2q23 + dCP modulation Vacuum oscillation maximum

  36. Long-Baseline Neutrino Oscillation Experiment (LBNE) • Particle Physics Project Prioritization Panel (P5) in the US; Report May ‘14 Bob Wilson @ Neutrino 2014

  37. Matter profile of the Earth … as seen by a neutrino (Preliminary Reference Earth Model) Core 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 Resonance energy (from ):

  38. Mantle-core-mantle profile (Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998) • Probability for L=11810 km Best-fit valuesfrom arXiv:1312.2878(first octant) ! Oscillation length ~mantle-core-mantle structureParametric enhancement. Core resonanceenergy Mantleresonanceenergy Naive L/E scalingdoes not apply! Thresholdeffects expected at: 2 GeV 4-5 GeV

  39. Emerging technologies: Atmospheric ns • Example: PINGU (“Precision IceCube Next Generation Upgrade“) • 40 additional strings, 60 optical modules each • Lower threshold, few Mtons at a few GeV • ORCA, INO: similar methods Mantle resonance energy (PINGU LOI, arXiv:1401.2046)

  40. Method 2: Disappearance probabilities • Works in vacuum, and even for q13=0 • Just flipping the sign of Dm2 is not sufficient • Example: Reactor experiment, L=53 kmProbabilities apparentlydifferent (unphysical effect!)

  41. Method 2: Disappearance probabilities • The disappearance Dm2 depends on the channel. Consequence e. g. • Now first oscillation maximamatch. Discrimination byhigher osc. Maxima. Need energy resolution! de Gouvea, Jenkins, Kayser, hep-ph/0503079; Nunokawa, Parke, Zukanovich, hep-ph/0503283 Zoom-in 3% (E/MeV)0.5

  42. Emerging technologies: Reactor experiments • Jiangmen Underground Neutrino Observatory(JUNO)[formerly Daya Bay-II] • L=53 km • Excellent energy resoluton (3% (E/MeV)0.5) requires O(100%) PMT coverage • Talk by Liangian WenPosters? Yu-Feng Li, arXiv:1402.6143 3% (E/MeV)0.5

  43. Global context LBNE 10kt if q23 varied as well Fig. 9 inarXiv:1305.5539; see also arXiv:1311.1822v2 • Bands: risk wrt q23 (PINGU, INO), dCP (NOvA, LBNE), energy resolution (JUNO) • LBNE and sensitivity also scales with q23! True NO POF IIIMatter and the Universe (version from PINGU LOI, arXiv:1401.2046,based on Blennow, Coloma, Huber, Schwetz, arXiv:1311.1822)

  44. Summary and conclusions • Mass hierarchy: may be tested in beginning of 2020s by “emerging technologies“, such as PINGU or JUNO PINGU has a good chance to be the first experiment to measure the mass hierarchy if timely; DESY involved • CP violation: requires a new long-baseline experiment, such as LBNE, T2HK, NuFact; P5 recognition milestone towards such a program at Fermilab • Other issues: q23 maximal? Octant?Sun and Earth tomography? New physics? • Light sterile neutrinos - best candidate for physics BnSM? Test short-baseline anomalies, measure neutrino X-secs, … • Perspectives for neutrino oscillations? Fantastic!

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