1 / 44

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.

winda
Télécharger la présentation

Perspectives for neutrino oscillations .

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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!

More Related