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Nature of neutrino mass

Nature of neutrino mass. Nature of neutrino mass. Smallness may indicate that nature of the neutrino mass (or at least what we observe in oscillations) differs from masses of other fermions. Is it of the same nature as the mass of electron or top quark?.

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Nature of neutrino mass

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  1. Nature of neutrino mass

  2. Nature of neutrino mass Smallness may indicate that nature of the neutrino mass (or at least what we observe in oscillations) differs from masses of other fermions Is it of the same nature as the mass of electron or top quark? Oscillations probe dispersion relation m m+ 2p E = E(p) ~ p + + 2 GF n + VBSM + … usual matter effect Lorentz violation CPT violation effect Additional terms can be Expanded: d E2 + z E3 + … A. Kostelecky ? mn(oscillations) = mn(kinematics)

  3. Hard vs. soft mn = mstandard + msoft(E,n) In general: medium (environment ) dependent (``soft’’) component mn2 = mstandard 2 + 2VE In matter: Can msoft dominate? mi = m0 tanh (li r(g/cm3)) P. De Holanda li = ( 0, 0.06, 3) m0 = 5 10-2 eV BOREXINO: absence of a significant Day-Night asymmetry for Be-neutrinos G. Bellini, et al 1104.2150 [hep-x] Excludes this possibility

  4. ``Soft'' neutrino mass? in the context of MaVaN scenario ln Exchange by very light scalar D B Kalplan, E. Nelson, N. Weiner , K. M. Zurek M. Cirelli, M.C. Gonzalez-Garcia, C. Pena-Garay V. Barger, P Huber, D. Marfatia nR nL f mf ~ 10-8 - 10-6 eV f = e, u, d, n lf fL fR chirality flip – true mass: lf ~ f/M Pl msoft = ln lfnf /mf mvac mvac + msoft In the evolution equation: medium and energy dependent mass generated by some short range physics (interactions) EW scale VEV

  5. Lorentz violation and neutrino oscillations V. Kostelecky et al arXiv:1012.5985 Effective Hamiltonian in vacuum L CPT, L 1 0 0 0 0 0 0 0 0 • 1 1 • 1 0 0 • 1 0 0 1 1 1 1 1 1 1 1 1 m2 2E cE5 + Heff = aE2 + Isotropic Lorentz and CPT violation in a chosen frame. Breaking boost symmetry. can be considered as effective mass which depends on energy Recall: usual oscillations in matter show CPT - Reproduces all established 3n –results: solar, atmospheric .. - Low energy excess of events in MiniBooNE • But: no 1-3 mixing effect at Double Chooze, RENO, Daya Bay • and suppressed e ffect in T2K and MINOS c = (104 GeV)-4

  6. Testing nature of mass New contributions can be identified by measuring the same D m2 and q in experiments with different environment: • in vacuum and in matter • in magnetic fields • at different energies • for neutrinos and antineutrinos LSND, MinoBooNE, MINOS ?

  7. Test of theory of oscillations Confronting different effects adiabatic vacuum conversion 2 oscillations D m MSW Sun q Phase effect Change of mixing in matter does not depend on oscillation phase Atmospheric vs. SBL oscillations Looking for mismatch of parameters determined from different effects in matter Modified dependence on parameters

  8. Searches for new neutrino states Challenge for theory, phenomenology experiment

  9. Sterile neutrino ns Light No weak interactions: - singlets of the SM symmetry group RH-components of neutrinos Couple with usual neutrinos via (Dirak) mass terms Mix with active neutrinos may have Majorana mass terms maximal mixing? Sov. Phys. JETP 26 984 (1968) in the context of idea of neutrino–antineutrino oscillations Quasi-sterile?

  10. New neutrino states - LSND, MiniBooNE 40 - 70 MeV 1 MeV ns • Warm Dark matter • Pulsar kick ~ 10 keV 1 keV • - LSND, MiniBooNE • Reactor anomaly • Calibration experiments • - Extra radiation 0.5 - 2 eV 1 eV (2 – 4) 10-3 eV - Solar neutrinos - Extra radiation in the Universe 10-3 eV rich phenomenology

  11. Phenomenology Accelerator Solar experiments neutrinos ns Atmospheric Supernova neutrinos neutrinos Cosmology Double beta decay Reactor experiments Beta decay DM searches

  12. Neutrino portal M S SO(10) A S Standard Model S S S S S also contact Interactions With q & l u d n l nR S S L L A uR dR S S S lR S S S S S Hidden sector with certain symmetries S S S s Planck scale physics

  13. Theoretical implications ne nm nt mee mem met … mmm mmt … … mtt Mass matrix meS mmS mtS mSS >> mab , maS nS … … … mSS tanqjS = mjS/mSS ~ 0.2 For mSS ~ 1 eV  dmij ~ - tanqiStanqjS mSS ~ 0.04 mSS In general can not be considered as small perturbation! Effect on mixing is small if J. Barry, W. Rodejohann, He Zhang arXiv: 1105.3911 meS mmS mtS have certain symmetry Active neutrino spectrum is quasi degenerate mSS ~ mab

  14. Applications mn = ma + dm Original active mass matrix e.g. from see-saw Induced mass matrix due to mixing with nu sterile dm can change structure (symmetries) of the original mass matrix completely (not a perturbation) produce dominant mt - block with small determinant Enhance lepton mixing Be origin of difference of Generate TBM mixing UPMNS and VCKM

  15. Cosmological bounds E Giusarma et al 1102.4774 [astro-ph] M Moresco et al, arXiv:1201.6658 LCDM Dm2 < 0.25 eV2 - WMAP 7 - SPT data - Compilation of direct measurements of the Hubble parameter, 0.1 < z < 1.75 Nn = 3.5 +/- 0.3, 1s 68 % 95% ACT instead of SPT Nn = 3.7 +/- 0.4, 1s • WMAP • SDSS (red galaxy clustering) • Hubble (prior on H0 ) run 1 (blue) Nn > 4 excluded at 95% CL + BBN • Supernova Ia Union • Compilation 2 (in add) run 2 (red)

  16. Evidences? Dm412 = 1 - 2 eV2 SAGE MiniBooNE LSND Double-Chooz Gallex,GNO G.Mention et al, arXiv: 1101.2755

  17. (3 + 1) scheme ne ns nt nm LSND/MiniBooNE: vacuum oscillations n4 P ~ 4|Ue4 |2|Um4 |2 restricted by short baseline exp. BUGEY, CHOOZ, CDHS, NOMAD Dm241 mass For reactor and source experiments n3 Dm231 P ~ 4|Ue4|2 (1 - |Ue4|2) n2 Dm221 n1 With new reactor data: ( 0.89 eV2) Dm412 = 1.78 eV2 - additional radiation in the universe - bound from LSS? Um4 = 0.23 Ue4 = 0.15

  18. MINOS and Steriles Main Injector Neutrino Oscillation Search Far detector: L = 735 km, 5400 t, steel, sampling calorimeter Fermilab – SOUDAN mine Near detector: L = 1.04 km, 1 kton Beam: 120 GeV protons,2.5 1020 p/year E = 1 - 10 GeV neutrinos Vacuum oscillations new feature Partial decoherence at production Decay pipe: lp ~ 630 m lp ~ ln

  19. MINOS bound In assumption of no-oscillations in ND |Um4|2 < 0.015 (90% CL) q13 = 0 q13 = 11.5o |Um4|2 < 0.019 (90% CL) LSND and MiniBooNE require: A. Sousa Dm412 < 0.5 eV2 |Um4|2 > 0.025 |Um4|2 < 0.015 (90% CL)

  20. MINOS bound nm-ns mixing In assumption of no-oscillations in ND |Um4|2 < 0.019 (90% CL) q13 = 11.5o LSND/MiniBooNE require: Dm412 > 0.5 eV2 |Um4|2 > 0.025 cosmology BUGEY+MINOS or modification of Cosmology: DN = 1.23 (add massless) w = - 1.11 BBN: chemical potential for ne J Hamann et al 1108.4136

  21. Confirmed? Now an excess is observed both in neutrino and antineutrino channels MiniBooNE In both channels an excess exists both at small (below 475 MeV) and at high energies An excess smoothly increases with decrease of energy starting from ~800 MeV L/E consistency with LSND It seems this is the same effect and there is no justification to split data Neutrino and antineutrino data are consistent No need to introduce second sterile Not possible to explain by oscillations? Large uncertainties in neutrino cross-sections Energy determination? Cosmology-MINOS

  22. ... or excluded? In spite of this…. New experiments: - Reactors NUCIFER, SCRAAM - MegaCurie strength sources - Accelerator SBL experiments OscSNS BooNE MicroBooNE (LArTPC), CERN-PS - Tens kilocurie source 50 kCi 144Ce - 144Pr (3 MeV) or 106Ru - 106 Rh (3.54 MeV) in BOREXINO, KamLAND, SNO+ C Giunti, M Laveder 1107.1452 [hep-ph] M. Cribier et al, 1107.2335 [hep-ex]]

  23. Looking for sterile in ice H Nunokawa O L G Peres R Zukanovich-Funchal Phys. Lett B562 (2003) 279 IceCube nm - ns oscillations with Dm2 ~ 1 eV2 are enhanced in matter of the Earth in energy range 0.5 – few TeV This distorts the energy spectrum and zenith angle distribution of the atmospheric muon neutrinos S Choubey JHEP 0712 (2007) 014 S Razzaque and AYS , 1104.1390, [hep-ph]

  24. Survival probability Neutrinos Antineutrinos MSW resonance dip

  25. Suppression factor S = N(osc.)/N(no osc.) Eth = 0.1 TeV

  26. Zenith angle distribution nS - mass mixing case Free normalization and tilt factor Part of the parameter space can be excluded

  27. Zenith angle distributions In general For different mixing schemes Varying |Ut0|2 < 3% stat. error Zenith angle distribution depends on admixture of nt in 4th mass state

  28. Can DeepCore IC help? Shift of phase quantifies effect of sterile neutrino With and without sterile Ratio

  29. Shining in sterile P. De Holanda A.S. 4p + 2e- 4He + 2ne + 26.73 MeV Adiabatic conversion n Oscillations in matter of the Earth

  30. Homestake BOREXINO SNO SuperKamiokande

  31. Problem? QArexp < QArLMA 2.55 +/- 0.25 SNU > 3.1 SNU No turn up of the spectrum in SK P. de Holanda, A.S. Phys. Rev. D69 (2004) 113002 hep-ph 0307266 Light sterile neutrino RD = Dm012 /Dm212 << 1 • << 1 - mixing angle of sterile- active neutrinos  dip in survival probability Motivation for the low energy solar neutrino experiments BOREXINO, KamLAND …

  32. Up-turn? SNO: LETA pp 7Be CNO 8B pep . BOREXINO gap ne- survival probability from solar neutrino data vs LMA-MSW solution KamLAND HOMESTAKE low rate SuperKamiokande

  33. Another possibility ne ns nt nm Very light sterile neutrino n3 m0 ~ 0.003 eV DE scale? M2 MPlanck M ~ 2 - 3 TeV Dm231 mass Motivated by n2 - solar neutrino data Dm221 n0 Dm2dip • additional radiation • in the Universe if mixed in n3 n1 no problem with LSS (bound on neutrino mass) sin2 2a ~ 10-3 can be tested in atmospheric neutrinos with DC IceCube sin2 2b ~ 10-1

  34. Survival probability - dip - wiggles

  35. Up-turns sin22a = 10-3 (red), 5 10-3 (blue) SK-I SNO-LETA P. De Holanda, A.S. SK-III Borexino SNO-LETA RD = 0.2 Dm2 = 1.5 10-5 eV2

  36. Extra radiation in the Universe Production of sterile in the Early universe Mixing of ns in n3 M Cirelli G Marandella A Strumia F Vissani n3 = cosb nt’ + sinb ns nt’ = cosq23nt + sinq23nm where Dm302 ~ 2.5 10-3 eV2 Atmospheric neutrinos: sin2b < 0.2 – 0.3 (90%) MINOS: sin2b < 0.23 (90%) tan2b

  37. Atmospheric neutrinos nmns resonance peak 10 – 15 GeV nt’ – ns resonance ER ~ 12 GeV Interplay of nmns and nm ntoscillations P. De Holanda, A. S. Phase shift and decrease of amplitude of oscillations: with sterile IceCube Deep Core difference ~ 20 % suppression of rate of events in the muon energy bins 5 – 15 GeV

  38. Implications M2 MPlanck m0 ~ 0.003 eV m0 = M ~ 2 - 3 TeV mixing h vEW M h = 0.1 sin2 2a ~ 10-3 a ~ vEW M sin2 2b ~ 10-1 b ~

  39. Challenges Challenging theory: deviations from standard oscillation formula? Conceptual issues: coherence at production, entangelment, etc. Collective effects in neutrino gases and SN neutrinos Theory of oscillations Discovery of relatively large 1-3 mixing – important implications for theory, phenomenology and experiment. Strong impact on further developments. 1-3 mixing Mass hierarchy: with NOvA, atmospheric neutrinos ICAL INO, DeepCore IC, PINGU-I, supernova neutrinos Next Measurements of the deviation of 23 mixing from maximal, CP- phase, absolute mass scale

  40. TBM: broken or accidental? Flavor symmetries - misleading approach? Quark-Lepton Complementarity (QLC)? Weak complementarity, self-complementarity Anarchy Quark-lepton unification, GUT. Mass - mixing relations Scales of new physics from eV to Planck… Theory • Possible scenario: • - Grand Unification, high scale seesaw, • fermion singlets with certain symmetries How to test this? LHC can test some low scale mechanisms of neutrino mass generation LFV processes…

  41. Challenge for neutrino physics. Controversial evidences. Their existence may strongly affect standard picture. On the other hand - open new possibilities Tests with solar and atmospheric neutrinos; IceCube, DC IceCube … Sterile Neutrinos Nature Dirac versus Majorana, hard –soft (environment dependents) of neutrino Searches for violation of the symmetries Lorentz, CPT with neutrinos is long lasting important program mass

  42. What is Next? 2012-2013 • - Double-CHOOZ - update • T2K - update • RENO - first results • - Daya-Bay ? 1-3 mixing • - MINOS – new analysis of data • IceCube – results of searches for sterile • DeepCore • MiniBooNE – final analysis of n data Steriles: • Nucifer • Source experiments: • cerium 144Ce KamLAND • - Planck - cosmological data - OscSNS BooNE - MicroBooNE (LArTPC), CERN-PS

  43. What is Next? Nature & Origins • - Double beta decay • GERDA, KamLAND-Zen, EXO-200 • LHC • MINOS, OPERA • Dark matter searches • …

  44. Lorentz violation and neutrino anomalies

  45. Searches for sterile Neutral current interactions Oscillations can not be neglected for near detector averaged oscillation effect

  46. Evolution Propagation basis ~ nf = U23 n ns ns ns ns ~ ~ nt nt n3 n3 A33 ~ ~ nm nm n2 n2 A22 decouples propagation projection projection S P(nmnm) = |cos2q23A22 + sin2q23A33 |2

  47. Level crossing H D m012 > (0.2 - 2) 10-5 eV2 ne n2m sin2 2a= 10-4 - 10-3 ns non-adiabatic level crossing nm/t n0m sterile resonances n1m density

  48. Level crossing scheme Normal mass hierarchy in the flavor block; m0 ~ 1 eV Three new level crossings |Ue4 |2 |Um4 |2 are large enough, so that evel crossings are adiabatic Ve - Vs = 2 GF (ne – nn /2)

  49. Mixing scheme and transitions ns ne na n0 n1 n2 U = Uq Ua Uq - rotation in 12-plane on q12 ns mixes inn0and n1 Ua - rotation in 01- plane on a Scheme of transitions n2 n2m ne n1m ne n1 interference  wiggles n0m n0 ns P(nene) ~ |Ue1mA11 + Ue0mA01|2 |Ue1 |2 + |Ue2 m|2|Ue2|2

  50. Bounds on mixing Illustrative fit in the simplest mixing scheme + 5% uncorrelated systematic errors LSND: sin2a > 0.04 Statistical errors + free normalization + tilt

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