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Neutrino physics Lecture 2: Neutrinos and new physics? Neutrino astrophysics

Neutrino physics Lecture 2: Neutrinos and new physics? Neutrino astrophysics. PhD Days 2012, IRTG of SFB 676 (Particles, Strings, and the Early Universe) DESY Hamburg Oct. 10, 2012 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents.

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Neutrino physics Lecture 2: Neutrinos and new physics? Neutrino astrophysics

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  1. Neutrino physicsLecture 2: Neutrinos and new physics? Neutrino astrophysics PhD Days 2012, IRTG of SFB 676(Particles, Strings, and the Early Universe)DESY Hamburg Oct. 10, 2012 Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Contents • Some more theoretical questions: • Is it possible that “new physics” shows up in the neutrino sector only? • How does the large q13 affect our understanding of (lepton) flavor? • Neutrino astrophysics • Neutrinos and the sources of the UHECR • Simulation of sources • Example:Neutrinos from Gamma-Ray Bursts (GRBs) • Matter effects in neutrino oscillations,neutrino oscillations in the Sun • Summary and conclusions

  3. Is it possible that “new physics” shows up in the neutrino sector only? Most discussed options in literature: Light sterile neutrinos (aka: light SM singlets) Heavy SM singlets ( non-unitary mixings) Non-standard interactions (aka: flavor changing neutral currents) NB: “new physics“ here in the sense of anomalous interactions, not in the sense of seesaws

  4. Evidence for sterile neutrinos?(addl. generations, not weakly interacting) • LSND/MiniBooNE • Reactor+gallium anomalies • Global fits (MiniBooNE @ Neutrino 2012) (B. Fleming, TAUP 2011) (Kopp, Maltoni, Schwetz, 1103.4570)

  5. Example: 3+1 framework(with addl. Dm2 ~ 1 eV2) • Well known tension between appearance and disapp. data (appearance  disappearance 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) Summary of options: Appendix of white paper arXiv:1204.5379

  6. also: “MUV“ Non-unitarity of mixing matrix? • Integrating out heavy fermion fields, one obtains neutrino mass and the d=6 operator (here: fermion singlets) • Re-diagonalizing and re-normalizing the kinetic terms of the neutrinos, one has • This can be described by an effective (non-unitary) mixing matrix e with N=(1+e) U • Relatively stroung bounds already, perhaps not so good candidate for future measurements(see e. g. Antusch, Baumann, Fernandez-Martinez, arXiv:0807.1003)

  7. Non-standard interactions • Typically described by effective four fermion interactions (here with leptons) • May lead to effects in oscillations (for g=d=e) • May also lead to source/detector effects How plausible is a modelleading to such NSI(and showing up inneutrino sector only)? acc: SM matter effect (later)

  8. Lepton flavor violation (d=6) • Charged leptonflavor violation • Strongbounds Ex.: NSI 4n-NSI CLFV e m ne nm ne nm ne ne e e e e • Non-standard neutrino interact. • Effects in neutrino oscillations in matter • Non-standard int. with 4n • Effects in environments with high neutrino densities (supernovae) BUT: These phenomena are not independent (SU(2) gauge invariance!)Is it possible that new physics is present in the neutrino sector only?

  9. Gauge-inv. d=8 operator? Davidson, Pena-Garay, Rius, Santamaria, 2003 • Decouple CLFV and NSI by SU(2) symmetry breaking with operator • Works at effective operator level, but are there theories allowing that? [at tree level] Project outneutrino field Project outneutrino field H, L: SU(2) doublets

  10. Systematic analysis for d=8 Feynman diagrams Basis (Berezhiani, Rossi, 2001) • Decompose all d=8 leptonic operators systematically • The bounds on individual operators from non-unitarity, EWPT, … are very strong! (Antusch, Baumann, Fernandez-Martinez, arXiv:0807.1003) • Need at least two mediator fields plus a number of cancellation conditions(Gavela, Hernandez, Ota, Winter, Phys. Rev. D79 (2009) 013007) Avoid CLFVat d=8:C1LEH=C3LEH Combinedifferentbasis elements C1LEH, C3LEH Canceld=8CLFV But these mediators cause d=6 effects Additional cancellation condition(Buchmüller/Wyler – basis)

  11. Is it possible/plausible that “new physics” shows up in the neutrino sector only? • Possible? • Yes, but at least non-standard four-fermion interactions require quite some fine-tuning • It is difficult to find models which would not produce effects elsewhere (LHC, EWPT, …) • Plausible? • Additional sterile generations are perhaps the most plausible new physics effect • Short-baseline anomalies (eV steriles)Caveat: would show up in cosmology … • Dark matter (keV steriles) • Non-unitarity (>> GeV steriles) • Leptogenesis (GUT-scale steriles)

  12. How does the large q13 affect our understanding of (lepton) flavor?

  13. The flavor problem Mixings? Masses? Degenerate neutrinos: m1 ~ m2 ~ m3 Hierarchical neutrinos: m1 << m2 << m3 How can one describe the differences amongthe generations and species? (hep-ph/0111263)

  14. Short seesaw-I mixing primer Block diag. Charged leptonmass terms Eff. neutrinomass terms Masses cf., charged current Rotates left-handed fields Depending on model, actual masses and mixings derived in non-trivial way!

  15. The TBM “prejudice“ • Tri-bimaximal mixings probably most discussed approach for neutrinos (Ul often diagonal) • Can be obtained in flavor symmetry models (e.g., A4, S4) • Consequence: q13=0  Obviously not! • Ways out for large q13?

  16. Impact on theory of flavor? q13 ? very small very large Structure:A4, S4, TBM, … Anarchy:Random draw? vs. TBM Corrections?CL sector?RGR running? Some structure + randomness:Froggatt-Nielsen? Currentstatus of field:Confusion? e.g. q12 = 35 + q13cosd(Antusch, King, Masina, …) Quark-leptoncomplementarity:q13 ~ qC? Different flavor symmetry?Other “ad hoc“ principles:part. patterns, texture zeros, …

  17. Anarchy? • Idea: perhaps the mixing parameters are a “random draw“? • Challenge: define measure which is independent of how random numbers generated • Result: large q13 “natural“, no magic needed (Hall, Murayama, Weiner, 2000; de Gouvea, Murayama, 2003, 2012)

  18. Hybrid alternatives? e.g. Meloni, Plentinger, Winter, PLB 699 (2011) 244 Charged leptons:Strong hierarchy,masses throughSM Yukawas Quarks:Strong hierarchiesSmall mixings Neutrinos:Mild (no?) hierarchy,large mixings, Majorana masses? Origin:physics BSM?LNV operator?  q13=0 Ansatz suitablefor hierarchies,such as Froggatt-Nielsen? Flavor symmetry,structure?Tri-bimaximal mixing“paradigm“?

  19. Neutrino astrophysics Focus: Neutrinos and the sources of the ultra-high energetic cosmic rays(UHECR)

  20. Nobel prize 2002 "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos“ • Raymond Davis Jr detected over 30 years 2.000 neutrinos from the Sun • Evidence for nuclear fusion in the Sun‘s interior! • Masatoshi Koshiba detectedon 23.02.1987 twelve of the 10.000.000.000.000.000 (1016) neutrinos, which passed his detector, from an extragalactic supernovaexplosion. • Birth of neutrino astronomy

  21. Neutrinos as cosmic messengers Physics of astrophysical neutrino sources = physics ofcosmic ray sources

  22. galactic extragalactic Evidence for proton acceleration, hints for neutrino production • Observation of cosmic rays: need to accelerate protons/hadrons somewhere • The same sources should produce neutrinos: • in the source (pp, pg interactions) • Proton (E > 6 1010 GeV) on CMB  GZK cutoff + cosmogenic neutrino flux UHECR(heavy?) In the source:Ep,max up to 1012 GeV? GZKcutoff?  want know more? G. Sigl

  23. Cosmic ray source(illustrative proton-only scenario, pg interactions) If neutrons can escape:Source of cosmic rays Neutrinos produced inratio (ne:nm:nt)=(1:2:0) Delta resonance approximation: Cosmogenic neutrinos p+/p0 determines ratio between neutrinos and high-E gamma-rays High energetic gamma-rays;typically cascade down to lower E Cosmic messengers

  24. The two paradigms for extragalactic sources:AGNs and GRBs • Active Galactic Nuclei (AGN blazars) • Relativistic jets ejected from central engine (black hole?) • Continuous emission, with time-variability • Gamma-Ray Bursts (GRBs): transients • Relativistically expanding fireball/jet • Neutrino production e. g. in prompt phase(Waxman, Bahcall, 1997) Nature 484 (2012) 351

  25. Neutrino emission in GRBs Prompt phasecollision of shocks: dominant ns? (Source: SWIFT)

  26. Neutrino detection:Neutrino telescopes • Example: IceCube at South PoleDetector material: ~ 1 km3 antarctic ice • Completed 2010/11 (86 strings) • Recent data releases, based on parts of the detector: • Point sources IC-40 [IC-22]arXiv:1012.2137, arXiv:1104.0075 • GRB stacking analysis IC-40+IC-59Nature 484 (2012) 351 • Cascade detection IC-22arXiv:1101.1692 • Have not seen anything (yet) • What does that mean? • Are the models too simple? • Which parts of the parameter space does IceCube actually test? • Particle physics reason? http://icecube.wisc.edu/ http://antares.in2p3.fr/

  27. Caveat (Ishihara @ Neutrino 2012) Energies~ PeV

  28. Simulation of sources

  29. Different interaction processes Resonances Differentcharacteristics(energy lossof protons;energy dep.cross sec.) Dres. Multi-pionproduction er (Photon energy in nucleon rest frame) Direct(t-channel)production (Mücke, Rachen, Engel, Protheroe, Stanev, 2008; SOPHIA;Ph.D. thesis Rachen)

  30. Source simulation: pg(particle physics) • D(1232)-resonance approximation: • Limitations: • No p- production; cannot predict p+/ p- ratio (Glashow resonance!) • High energy processes affect spectral shape (X-sec. dependence!) • Low energy processes (t-channel) enhance charged pion production • Solutions: • SOPHIA: most accurate description of physicsMücke, Rachen, Engel, Protheroe, Stanev, 2000Limitations: Monte Carlo, slow; helicity dep. muon decays! • Parameterizations based on SOPHIA • Kelner, Aharonian, 2008Fast, but no intermediate muons, pions (cooling cannot be included) • Hümmer, Rüger, Spanier, Winter, ApJ 721 (2010) 630Fast (~1000 x SOPHIA), including secondaries and accurate p+/ p- ratios • Engine of the NeuCosmA („Neutrinos from Cosmic Accelerators“) software+ time-dependent codes from:Hümmer, Rüger, Spanier, Winter, ApJ 721 (2010) 630

  31. “Minimal“ (top down) n model Q(E) [GeV-1 cm-3 s-1] per time frameN(E) [GeV-1 cm-3] steady spectrum Dashed arrows: include cooling and escape Input: B‘ Opticallythinto neutrons from: Baerwald, Hümmer, Winter,Astropart. Phys. 35 (2012) 508

  32. Kinetic equations • Energy losses in continuous limit:b(E)=-E t-1lossQ(E,t) [GeV-1 cm-3 s-1] injection per time frameN(E,t) [GeV-1 cm-3] particle spectrum including spectral effects • For neutrinos: dN/dt = 0 (steady state) • Simple case: No energy losses b=0 Injection Energy losses Escape often: tesc ~ R

  33. Typical source models • Protons typically injected with power law (Fermi shock acceleration!) • Target photon field typically: • Put in by hand (e.g. obs. spectrum: GRBs) • Thermal target photon field • From synchrotron radiation of co-accelerated electrons/positrons (AGN-like) • From a more complicated combination of radiation processes ?

  34. Peculiarity for neutrinos: Secondary cooling Example: GRB Decay/cooling: charged m, p, K • Secondary spectra (m, p, K) loss-steepend above critical energy • E‘c depends on particle physics only (m, t0), and B‘ • Leads to characteristic flavor composition and shape • Very robust prediction for sources? [e.g. any additional radiation processes mainly affecting the primaries will not affect the flavor composition] • The only way to directly measure B‘? nm Pile-up effect Flavor ratio! Spectralsplit E‘c E‘c E‘c Adiabatic Baerwald, Hümmer, Winter,Astropart. Phys. 35 (2012) 508; also: Kashti, Waxman, 2005; Lipari et al, 2007

  35. Example:Neutrinos from GRBs

  36. The “magic“ triangle g Satellite experiments(burst-by-burst) Model-dependent prediction GRB stacking(next slides) Partly common fudgefactors: how many GRBsare actually observable?Baryonic loading? … ?(energy budget, CR “leakage“, quasi-diffuse extrapolation, …) Robust connectionif CRs only escape as neutrons produced in pg interactions CR n Neutrino telescopes (burst-by-burst or diffuse) CR experiments (diffuse)

  37. g GRB stacking n (Source: IceCube) • Idea: Use multi-messenger approach • Predict neutrino flux fromobserved photon fluxesevent by event (Source: NASA) Coincidence! Neutrino observations(e.g. IceCube, …) GRB gamma-ray observations(e.g. Fermi GBM, Swift, etc) Observed:broken power law(Band function) (Example: IceCube, arXiv:1101.1448) E-2 injection

  38. Gamma-ray burst fireball model:IC-40 data meet generic bounds • Generic flux based on the assumption that GRBs are the sources of (highest energetic) cosmic rays(Waxman, Bahcall, 1999; Waxman, 2003; spec. bursts:Guetta et al, 2003) Nature 484 (2012) 351 IC-40+59 stacking limit • Does IceCube really rule out the paradigm that GRBs are the sources of the ultra-high energy cosmic rays?

  39. IceCube method …normalization • Connection g-rays – neutrinos • Optical thickness to pg interactions:[in principle, lpg ~ 1/(ngs); need estimates for ng, which contains the size of the acceleration region] ½ (charged pions) x¼ (energy per lepton) Energy in protons Energy in neutrinos Fraction of p energyconverted into pions fp Energy in electrons/photons (Description in arXiv:0907.2227; see also Guetta et al, astro-ph/0302524; Waxman, Bahcall, astro-ph/9701231)

  40. IceCube method … spectral shape • Example: 3-ag 3-bg 3-ag+2 First break frombreak in photon spectrum(here: E-1 E-2 in photons) Second break frompion cooling (simplified)

  41. Revision of neutrino flux predictions Analytical recomputationof IceCube method (CFB): cfp: corrections to pion production efficiency cS: secondary cooling and energy-dependenceof proton mean free path(see also Li, 2012, PRD) G ~ 1000 G ~ 200 Comparison with numerics: WB D-approx: simplified pg Full pg: all interactions, K, …[adiabatic cooling included] (Baerwald, Hümmer, Winter, Phys. Rev. D83 (2011) 067303;Astropart. Phys. 35 (2012) 508; PRL, arXiv:1112.1076)

  42. Systematics in aggregated fluxes • z ~ 1 “typical“ redshift of a GRB • Neutrino flux overestimated if z ~ 2 assumed(dep. on method) • Peak contribution in a region of low statistics • Systematical error on quasi-diffuse flux (90% CL) ~ 50% for 117 bursts, [as used in IC-40 analysis] Weight function:contr. to total flux Distribution of GRBsfollowing star form. rate (strongevolutioncase) 10000 bursts (Baerwald, Hümmer, Winter, Astropart. Phys. 35 (2012) 508)

  43. Quasi-diffuse prediction • Numerical fireball model cannot be ruled out with IC40+59 for same parameters, bursts, assumptions • Peak at higher energy![optimization of future exps?] “Astrophysical uncertainties“:tv: 0.001s … 0.1sG: 200 …500a: 1.8 … 2.2ee/eB: 0.1 … 10 (Hümmer, Baerwald, Winter, Phys. Rev. Lett. 108 (2012) 231101)

  44. Comparison of methods/models from Fig. 3 of Hümmer et al, arXiv:1112.1076, PRL;origin of target photons not specified from Fig. 3 of Nature 484 (2012) 351; uncertainties from Guetta, Spada, Waxman, Astrophys. J. 559 (2001) 2001:target photons from synchrotron emission/inverse Compton completely model-independent (large collision radii allowed): He et al, Astrophys. J. 752 (2012) 29 (P. Baerwald)

  45. Particle physics depletion/reason:Neutrino decay? Decay hypothesis: n2 and n3 decay with lifetimes compatible with SN 1987A bound • Reliable conclusions from astrophysical neutrino flux bounds require cascade (ne) measurements! (from: Baerwald, Bustamante, Winter, JCAP, 2012)

  46. Neutrinos-cosmic rays n CR • If charged p and n produced together: • GRB not exclusive sources of UHECR? CR leakage? Consequences for (diffuse) neutrino fluxes Fit to UHECR spectrum (Ahlers, Gonzalez-Garcia, Halzen, Astropart. Phys. 35 (2011) 87)

  47. Matter effects in neutrino oscillations … or how to measure the mass hierarchy

  48. 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 • Matter effects proportional to electron density ne and baseline • Hamiltonian in matter (matrix form, flavor space): Y: electron fraction ~ 0.5 (electrons per nucleon)

  49. Matter profile of the Earth… as seen by a neutrino Core (PREM: Preliminary Reference Earth Model) Innercore

  50. Parameter mapping(two flavors, constant matter density) • 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 ~ 7 GeV- r ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 3 GeV  MH Resonance energy:

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