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Neutrino Physics

Neutrino Physics. After KamLAND. A. Yu. Smirnov. AS ICTP, Trieste, Italy. ``KamLAND: Before and After’’. Solar Neutrinos. Reconstruction of the neutrino mass spectrum. Atmospheric neutrinos. Supernova neutrinos. The end of era of the neutrino anomalies?. Before and After.

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Neutrino Physics

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  1. Neutrino Physics After KamLAND A. Yu. Smirnov AS ICTP, Trieste, Italy • ``KamLAND: Before and After’’ • Solar Neutrinos • Reconstruction of the neutrino mass spectrum • Atmospheric neutrinos • Supernova neutrinos • The end of era of the neutrino anomalies?

  2. Before and After After After CPT Confirmation KamLAND of LMA MSW ``Neutrino Physics after KamLAND’’ started much before announcement of the first results Since 1998 -1999 most of the papers - in context of the LMA solution (phenomenology, implications etc..) Strong evidence of oscillations of the atmospheric neutrinos 1998 is the turn point ``Revolution 98’’: SMA MSW solution of the solar neutrino problem - disfavored The prejudice of small mixing was destroyed A Yu Smirnov

  3. Flavors and Masses Flavor states: Mixing: ne nt nm Flavor states Mass eigenstate = Eigenstates of the CC weak interactions m3 n3 Sterile neutrinos no weak interactions ? ns mass m2 n2 Mass eigenstates: m1 n1 n1 n2 n3 m1 m2 m3 Neutrino mass and flavor spectrum A Yu Smirnov

  4. Mixing and flavor states n2 = sinq ne + cosq nm n1 = cosq ne - sinq nm vacuum mixing angle coherent mixture of mass eigenstates ne = cosq n1 + sinq n2 n1 wave packets ne n2 Dm 2 2E Df = ---- l Interference of the parts of wave packets with the same flavor depends on the phase difference Df between n1 and n2 Dm2 = m22 - m12 A Yu Smirnov

  5. KamLAND Kamioka Large Anti-Neutrino Detector 1 kton of LS Reactor long baseline experiment 150 - 210 km Liquid scintillation detector ne + p---> e+ + n Epr > 2.6 MeV Total rate energy spectrum of events LMA precise determination of the oscillation parameters 10% accuracy Detection of the Geo-neutrinos Epr > 1.3 MeV

  6. KamLAND results K. Eguchi et al., Phys. Rev. Lett., 90, 021802 (2003) Spectrum Rate Nobs = 54, Nbg ~ 1 Nobs/Nexp = 0.611 + 0.094 Nexp = 86.8 + 5.6 A Yu Smirnov

  7. KamLAND: Culmination of ~ 40 years of solar neutrino studies CPT has confirmed the LMA MSW solution excluded other solutions at least as dominant mechanisms further shifted the allowed region and best fit point to larger Dm2 (5 7) 10-5 eV2 The lower bound: Dm2 > (4 - 5) 10-5 eV2 looks rather solid Mixing is practically unaffected Confirmation of the whole oscillation picture including oscillations of the atmospheric neutrinos A Yu Smirnov

  8. Solar Neutrinos 4p + 2e- 4He + 2ne + 26.73 MeV Adiabatic conversion in matter of the Sun electron neutrinos are produced F = 6 1010 cm-2 c-1 r : (150 0) g/cc total flux at the Earth Oscillations in vacuum n Oscillations in matter of the Earth J.N. Bahcall

  9. Solar neutrino problem 1.0 Deficit of signal 0.8 Deficit is different for experiments with different tresholds Ga 0.6 SK CC/NC Signal/SSM SNO 0.4 Cl R(CL) < R(SK) SNO: direct evidence of the neutrino flavor conversion 0.2 0 Threshold energy CC/NC ~ 0.34 Still there no observations of signatures of a particular mechanism of neutrino conversion Distortion of the boron neutrino spectrum Day-Night asymmetry Seasonal variation A Yu Smirnov

  10. Large mixing MSW solution solar data solar data + KamLAND P. de Holanda, A.S. sin2q13 = 0.0 Dm2 = 6.8 10-5 eV2 Dm2 = 7.3 10-4 eV2 tan2q = 0.40 tan2q = 0.41

  11. LMA MSW solution An example: E = 10 MeV Resonance layer: nR Ye = 20 g/cc RR= 0.24 Rsun n2m In the production point: sin2qm0 = 0.94 cos2 qm0 = 0.06 n2m n1m Evolution of the eigenstate n2m Flavor of neutrino state follows density change

  12. Inside the Earth. Regeneration Oscillations in the matter of the Earth n2 n2 core Regeneration of the ne flux Day - Night asymmetry Variations of signal during nights (zenith angle dependence), Seasonal variations mantle Spectrum distortion Parametric effects for the core crossing trajectories

  13. Profile of the effect Adiabatic solution npp nBe nB Survival probability Earth matter effect sin2q I III II ln / l0 ~ E Conversion with small oscillation effect Non-oscillatory transition Oscillations with small matter effect Conversion + oscillations A Yu Smirnov

  14. Conversion inside the Sun tan2q = 0.41, Dm2 = 7.3 10-5 eV2 surface core survival probability survival probability resonance E = 14 MeV E = 2 MeV y y distance distance survival probability survival probability E = 0.86 MeV E = 6 MeV y y

  15. freg Inside the Earth Averaging of oscillations, divergency of the wave packets incoherent fluxes of n1 and n2 arrive at the surface of the Earth n1and n2 oscillate inside the Earth ln /l0 Regeneration of the ne flux ln /l0 ~ 0.03 E = 10 MeV P ~ sin2 q + freg freg ~ 0.5 sin 22q ln /l0 The Day -Night asymmetry: Oscillations + adiabatic conversion AND = freg/P ~ 3 - 5 % distance A Yu Smirnov

  16. Is the Solar Neutrino Problem Resolved? Accepting the first KamLAND result LMA CPT All other possibilities are excluded as leading effects Still the allowed region should be diminished to identify physical processes: Averaged vacuum oscillations with small matter corrections High Dm2 Non-oscillatory adiabatic conversion (for E > 5 MeV) Low Dm2 Small mixing: Resonance description is valid Maximal mixing: ``Resonance’’ is at zero density A Yu Smirnov

  17. Delta m2 and mixing P.de Holanda, A.S. hep-ph/0212270 Two stages AND % Identification of the unique region: 2n analysis, sub-leading effects (13 -mixing) can be neglected Precision measurements: Possible sub-leading effects should be included. Generic 3n analysis should be performed. Problem of degeneracy of parameters appears CC NC Lines of constant CC/NC ratio and Day-Night asymmetry at SNO A Yu Smirnov

  18. LMA: Consistency Checks Over determine solution, cross checks in the b.f. point AND(SNO) = 2 - 5 % , ADN(SK) = 2 - 3 % Day -Night Asymmetries: Spectrum distortion: Turn up at low energies: 5 - 10 % Rate at the intermediate energies BOREXINO/KamLAND R = (0.6 - 0.7)RSSM Small (unobservable) effect: AWS < 0.5% Seasonal variations Low energy experiments - further confirmation of LMA - precise determination of the neutrino parameters - searches for physics ``beyond the LMA’’ Implications A Yu Smirnov

  19. Homestake Anomaly? Pull-off diagrams for the best fit points of the l- and h- LMA regions (2 - 2.5) s pull Statistical fluctuation ? Systematics? Related to time variations of rate? Neutrino properties: conversion driven by second Dm2 Additional deep in the suppression pit at E ~ 1 MeV? QAr(LMA) > QAr(Homestake) A Yu Smirnov

  20. Spectrum distortion at SNO P.Krastev, A.S. Turn up of the spectrum at low energies is expected 6 8 10 12 Te

  21. LMA + SMA(sterile) New (sterile) neutrino with m ~ (2 - 3) 10-3 eV which mixes weakly with active neutrinos Survival probability npp nBe nB Nonadiabatic conversion in ns - ns resonance sin2q I ln / l0 ~ E Reduced Ar-production rate No (or weak) turn up of the spectrum Reduced rate in BOREXINO Smaller Germanium production rate or smaller sin2q and larger original boron neutrino flux A Yu Smirnov

  22. Solar Neutrinos versus KamLAND Parameters from the 2n analysis: The equality is satisfied within 1s Dm2 tan2q Dm2 tan2q Solar KamLAND neutrinos Gives hint that CPT is OK Further checks of the equality Possible deviations (mismatch of parameters if the fit is done in terms of 2n mixing): CPT-violation Physics Beyond the LMA If some effect influences KamLAND signal it should also show up in the solar neutrinos Some effect can influence solar neutrinos but not KamLAND result Inverse is not correct: A Yu Smirnov

  23. Solar neutrinos have much higher sensitivity to Physics Beyond the LMA Dm2 - q region of sensitivity is much larger for solar neutrinos than for KamLAND Additional small Dm2 or/and q can strongly influence the solar neutrinos but not KamLAND Magnetic moment: the Earth magnetic field is too small Non-standard interactions (NSI) of neutrinos do not change the KL signal since the matter effect is small Even in the CPT conserving case one can find Dm2 , q Dm2 , q = solar KL A Yu Smirnov

  24. Testing the theory of conversion Solar neutrinos KamLAND Adiabatic conversion (MSW) Vacuum oscillations Matter effect dominates (at least in the HE part) Matter effect is very small Non-oscillatory transition the oscillation phase is irrelevant Oscillation phase is crucial for observed effect Vacuum oscillation formula Adiabatic conversion formula Dm2 , q Coincidence of these parameters determined from the solar neutrino data and from KamLAND results testifies for the correctness of the theory (phase of oscillations, matter potential, etc..) See also F.L. Fogli et al., hep-ph/0211414

  25. Beyond LMA MSW Physics of sub-leading effects Signatures Implications LMA MSW + ... Magnetic moment, magnetic fields inside the Sun Searches for ne flux + SFP Time variations Beyond single Dm2 context CC/NC Additional distortion of spectrum + nu-sterile Additional contribution to the matter effect + NSI (non-standard neutrino interaction) + VEP (violation of equivalence principle) A Yu Smirnov

  26. Searches for Nu-sterile ne -> 1 - h na + h ns Single Dm2 context P. de Holanda, A.S. hep-ph/0211264 3s 2s 1s h The 3s allowed region for h = 0.0, 0.2, 0.4, 0.6 (from right to left) The allowed region in the h - fB (boron neutrino flux) plane for different confidence levels A Yu Smirnov

  27. LMA + SFP Spin-flavor precession (resonance, non-resonance) ``Post-KamLAND’’ study in the context of single E. Akhmedov, J. Pulido hep-ph/0209192 Dm2 = Dm2LMA The effect (neutrino spin flip) is in the central regions of the Sun (radiative zone) B > 10 MG Signature: Appearance of the antineutrino ne flux 2 2 mn 10-12 mB F( ne) F( ne) B 100 MG (for the boron neutrinos) = 1.5% At the present SK bound (unless Voloshin’s cancellation, or polarization suppression occurs) e L2 Magnetic moment: mn ~ mn (natural* value) For the cut energy L = 100 GeV and mn = 1 eV: unobservable? mn ~10-16 mB Beyond single Dm2 : if for second Dm2 << Dm2LMA effect can be much larger

  28. Solar Neutrino Astrophysics Back to the original task: The spectroscopy of Solar Neutrinos J.N.Bahcall G.T.Zatsepin V.A. Kuzmin to study interior properties of the Sun Diagnostics of the Sun Determination of the original solar neutrino fluxes In a sense these fluxes do not exist since neutrino conversion starts already in the neutrino production region Still we can introduce these fluxes since there is no back influence of neutrino conversion on the solar characteristics and production of neutrinos. Conversion effects can be subtracted J. N. Bahcall, M. Gonzalez-Garcia C. Pena-Garay astro-ph/0212331 Determine neutrino fluxes from pp- and CNO - cycles Searches for time variations of fluxes A Yu Smirnov

  29. Reconstruction of neutrino mass and flavor spectrum Precise determination of parameters Fundamental problem of particle physics Physics beyond the Standard Model Implications for astrophysics and Cosmology Mechanism of neutrino mass generation Unification of particles and forces, GU Fermion mass problem A Yu Smirnov

  30. Mass spectrum and mixing ne nm nt |Ue3|2 ? n3 n2 Dm2sun n1 mass Dm2atm Dm2atm mass |Ue3|2 n2 Dm2sun n1 n3 Normal mass hierarchy (ordering) Inverted mass hierarchy (ordering) Type of mass spectrum: with Hierarchy, Ordering, Degeneracy absolute mass scale Type of the mass hierarchy: Normal, Inverted Ue3 = ? A Yu Smirnov

  31. Accomplishing Standard Picture sinq13 = |Ue3| Normal Inverted Type of mass hierarchy or ordering: sign Dm232 hierarchical partially degenerate quasi-degenerate Absolute scale of neutrino mass Type of mass spectrum m1 Dirac CP-violating phase, d Leptonic Unitarity triangle Dirac Majorana Nature of neutrinos: Majorana CP-violating phases, r, s D m221 Precision measurements of oscillation parameters tan2q12 Deviation from maximal mixing Dm232 Search for new neutrino states sin2 2q23 A Yu Smirnov

  32. Standard and Non-Standard Beyond the Standard Standard picture Three neutrinos New neutrino states Sterile neutrinos Massive, m < 1 eV New interactions ~ Large anomalous dipole moments Bi-large or Large-maximal mixing Exotics Smallness of neutrino mass is related to Majorana nature Effects of violation of Lorentz invariance CPT, Equivalence principle ... Oscillations and matter conversion -- common phenomena A Yu Smirnov

  33. Atmospheric Neutrinos: Any problem? is the dominant mechanism of the atmospheric neutrino conversion nm <-> nt Very compelling evidence that vacuum oscillations - SuperKamiokande - K2K - MACRO - SOUDAN KamLAND gives an additional confirmation of the oscillation picture - confirms oscillations - large/maximal mixing in the lepton sector Nothing statistically significant beyond this picture ne oscillations sterile neutrinos CP-violation CPT-violation specific oscillation effects CR physics with atmospheric nu Searches for What is the next?

  34. Oscillations of atmospheric nu_e Oscillations of electron (anti) neutrino must appear at some level even for q13 = 0 due to the solar oscillation parameters After KamLAND Excess of the e-like events in certain energy range with - specific energy and - zenith angle dependence Signature: Due to solar Dm212, q12 Due to non-zero q13 and atmospheric Dm213 Multi-GeV events Sub-GeV events Interference

  35. Oscillations due to solar dm2 and theta Excess of the e-like events in the sub-GeV Fe = Fe0 (Pee + r Pme) Fe Fe0 - 1 = P2 ( r c232 - 1) ``screening factor’’ P2 = P(Dm212 , q12) is the 2n transition probability In the sub-GeV sample r = Fm0 / Fe0 ~ 2 The excess is zero for maximal 23- mixing Zenith angle dependence of the e-like events 0.Peres, A.S., hep-ph/0201069

  36. Excess of the e-like events Fe Fe0 e = - 1 In the best fit points of the l- and h- LMA regions sin2 2q23 el , % e h, % Excess increases with Dm2 0.91 2.8 4.8 0.96 1.9 3.2 0.99 0.9 1.6 Once the LMA parameters are known: restrict deviation of 23-mixing from maximal by measuring e A Yu Smirnov

  37. S_13 CHOOZ Excess of the e-like events in multi-GeV region U - D U + D A U/D = 2 A U/D, % 5.0 5.8 6.7 7.5 U: cos QZ = (-1 -- -0.6) 8.3 8.8 D: cos QZ = (0.6 -- 1) Contours of constant up - down asymmetry of the e -like events s232 = 0.5 Akhmedov, A. Dighe, P. Lipari, A.S. A Yu Smirnov

  38. Induced Interference Zenith angle dependence of the e-like events Excess of the e-like events in the sub-GeV Fe Fe0 - 1 = P2 ( r c232 - 1) - r s13 sin2q23 Re (A*ee Aem) - s213 [2(1 - r s223 ) + P2 (r - 2)] P2 = |Aem|2 is the 2n transition probability Interference term: - linear in s13 -no screening effect - has opposite sign for neutrinos and antineutrinos - maximal if Dm212 = 7 10-5 eV2 Dm212 = 5 10-5 eV2 Can be dominant if 23-mixing is maximal: s13 0.3 eint ~ 5% (in maximum) 0.Peres, A.S., hep-ph/0201069

  39. Sterile Neutrino H. Nunokawa, O.L.G.Peres, R. Zukanovich Funchal, hep-ph/0302039 Fourth neutrino with Dm2 ~ Dm 2 LSND ~ 0.5 eV2 resonance in the 0.5 - 1.5 TeV range For (3+1) scheme resonances are in ne - ns , nm/t - nschannels IceCube (3) (3+1) (3 +1) (3) Upward-going muons Cascade events (induced by the CC interactions of electron, and tau neutrinos and by the NC scattering) Searches new neutrino states Observation of the parametric effects

  40. Supernova neutrinos r ~ (1011 - 10 12 ) g/cc 0 E (ne) < E (ne) < E ( nx ) A Yu Smirnov

  41. SN neutrinos and MSW effect The MSW effect can be realized in very large interval of neutrino masses ( Dm2 ) and mixing Dm2 = (10-6 - 107) eV2 sin2 2q = (10-8 - 1) Very sensitive way to search for new (sterile) neutrino states A way to probe the hierarchy and value of s13 Type of the mass hierarchy The conversion effects strongly depend on Strength of the 1-3 mixing (s13) Small mixing angle realization of the MSW effect In the case of normal mass hierarchy: ne <-> nm /nt almost completely If 1-3 mixing is not too small s132 > 10- 5 F(ne) = F0( nm) hard ne- spectrum No earth matter effect in ne - channel but in ne - channel strong non-oscillatory conversion is driven by 1-3 mixing Neutronization ne - peak disappears

  42. LBL experiments with SN neutrinos Two well separated detectors are used Comparison of signals from the two detectors: oscillation effects between them and also test properties of the original flux Beam uncertainties can be controlled if Properties of medium are know D1 This is realized for oscillations of SN neutrinos inside the Earth: D2 Fluxes arriving at the surface of the earth are the same for both detectors L1 n L2 If sin2q13>10-4 an appearance of the Earth matter effect in ne or ( ne ) signal will testify for normal (inverted) mass hierarchy of neutrinos e.g. n

  43. Neutrinos from SN1987A after KamLAND Certainly, neutrino signal from SN1987A has been affected by conversion inside the star and probably oscillations in the matter of the Earth Effects of neutrino conversion must be taken into account in the analysis of neutrino data: - determination of parameters of the original neutrino fluxes, - comparison of signals in different detectors The observable conversion effect depends also on the difference of original spectra of the electron and muon/tau antineutrinos A Yu Smirnov

  44. Conversion of SN (anti)neutrinos Inside the star |< ne | n1 >|2 = cos2q ne -> n1 adiabatic transitions: nm / nt-> n2 |< ne | n2 >|2 = sin2q Electron antineutrino flux at the detector: Fe = cos2qFe0 + sin2q Fx0 Fe = Fe0 + sin2q DF0 DF0 = Fx0 - Fe0 where Fe0, Fx0 are the original fluxes of ne and nm Inside the Earth sin2q --> p = (1 - P1e) n1 and n2 oscillate P1e is the probability of n1 -> ne transition in the matter of the Earth Fe = Fe0 + p D F0 A Yu Smirnov

  45. SN87A and the Earth matter effect C.Lunardini A.S. p F(ne) = F0(ne) + p DF0 p = (1 - P1e) is the permutation factor P1e is the probability of n1-> ne transition inside the Earth DF0 = F0(nm) - F0(ne) p depends on distance traveled by neutrinos inside the earth to a given detector: 4363 km Kamioka d = 8535 km IMB 10449 km Baksan p Can partially explain the difference of energy distributions of events detected by Kamiokande and IMB: at E ~ 40 MeV the signal is suppressed at Kamikande and enhanced at IMB

  46. Spectra of events cos2q = 0.5 Dm2 = 2.75 10 -5 eV2 T(ne) = 3.5 MeV, T(nm) = 7 MeV C. Lunardini, A.S. PRD 63, 073009 (2001) Kamiokande IMB original flux Number of events Number of events after conversion in the star Energy, MeV Energy, MeV A Yu Smirnov

  47. Reconciling Kamiokande and IMB Bands of equal oscillation phases: fIMB(40MeV) ~ kp fK2(40MeV) ~ (1/2 + k)p C. Lunardini, A.S. PRD 63 073009 A Yu Smirnov

  48. Probing mass hierarchy and 1-3 mixing Extreme cases A. Normal hierarchy large 1-3 mixing B. Inverted hierarchy large 1-3 mixing C. Very small 1-3 mixing composite, weakly (sin 2q ~ 1/4) mixed composite, weakly (sin 2q ~ 1/4) mixed unmixed, hard ne-spectrum composite, strongly (cos2q ~ 3/4) permuted composite, strongly (cos2q ~ 3/4) permuted ne-spectrum unmixed, hard Earth matter effect in antineutrino channel in neutrino channel both in neutrino and antineutrino channels Large 1-3 mixing: sin2q13 > 10-4 A Yu Smirnov

  49. Observables the observed spectra of ne and ne- events Ne(E > EL) Ne(E > EL) Ratio of the neutrino and antineutrino events in the tails R (EL, EL) = Ntot Ntot Ratio of the total number of neutrino and antineutrino events Rtot = <E> <E> rE = Ratio of the average energies <G> <G> Ratio of the width of the spectra: rG = A Yu Smirnov

  50. Scatter Plots Ratio of the low energy events Rtot S Rtail Rtail A Yu Smirnov

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