1 / 40

Neutrinos: At the Heart of the Matter?

Neutrinos: At the Heart of the Matter?. Kevin McFarland University of Rochester 5 August 2012. Neutrino Frontier. And each time we look over the horizon…. Foci for Current Work. Neutrinos as particles Masses Mixing and CP violation Neutrinos as probes Of the large Of the small. γ ν.

cole
Download Presentation

Neutrinos: At the Heart of the Matter?

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. Neutrinos:At the Heart of the Matter? Kevin McFarlandUniversity of Rochester5 August 2012 K. McFarland, Neutrino Frontier

  2. Neutrino Frontier K. McFarland, Neutrino Frontier

  3. And each time we look over the horizon… K. McFarland, Neutrino Frontier

  4. Foci for Current Work • Neutrinos as particles • Masses • Mixing and CP violation • Neutrinos as probes • Of the large • Of the small γν Figure from C. Walter, Super-Kamiokande Collaboration K. McFarland, Neutrino Frontier

  5. Foci for Current Work • Neutrinos as particles • Masses • Mixing and CP violation • Neutrinos as probes • Of the large • Of the small Figure from G. Kane, Scientific Am., 2003 CERN Publications K. McFarland, Neutrino Frontier

  6. Neutrino Flavor • Neutrinos were discovered by • the final state positron tags flavor • we’ve seen neutrinosproduce all threecharged leptons in weak interactions • The Z boson decays into three (and only three) neutrinos K. McFarland, Neutrino Frontier

  7. Neutrino FlavorMixing • If neutrinos mass states mix to formflavors (Pontecorvo) • and the masses are different… • flavors of neutrinos can change in flight • Explains Davis’ “solar neutrino puzzle” • since only electron flavor neutrinosinduce ν+n→p+e- K. McFarland, Neutrino Frontier

  8. Neutrino Flavor Oscillation • Each neutrino wavefunctionhas a time-varying phase in its rest frame, • Now, imagine you produce a neutrino of definite momentum but is a mixture of two masses, m1, m2 • so pick up a phase difference in lab frame K. McFarland, Neutrino Frontier

  9. Neutrino Oscillation (cont’d) • Phase differencecan cause change of flavor in a vacuum • more generally, mixing need not be maximal only two generations for now! K. McFarland, Neutrino Frontier

  10. Neutrino Oscillation (cont’d) e- density appropriate units give the usual numerical factor1.27 GeV/km-eV2 • For two generations… • Oscillations require mass differences • Oscillation parameters are mass-squared differences, dm2, and mixing angles, q. • One correction to this is matter… changes q, L dep. Wolfenstein, PRD (1978) K. McFarland, Neutrino Frontier

  11. Solar Neutrinos: SNO • D2O target uniquely observed: • charged-current • neutral-current • The former is onlyobserved for ne(lepton mass) • The latter for all types • Solar flux is consistentwith models • but not all ne at earth K. McFarland, Neutrino Frontier

  12. KAMLAND • Sources wereJapanesereactors • 150-200 kmfor most offlux. Rate uncertainty ~6% • 1 kTonscint. detector inold Kamiokande cavern • overwhelming confirmationthat neutrinos change flavorin the sun via mattereffects K. McFarland, Neutrino Frontier

  13. Atmospheric Neutrinos • Neutrino energy: few 100 MeV – few GeV • Flavor ratio robustly predicted • Distance in flight: ~20km (down) to 12700 km (up) K. McFarland, Neutrino Frontier

  14. Super-Kamiokande • Super-Kdetector hasexcellent e/mseparation • Up / down difference: L/E • Muons distorted, electrons not; so mostly 2004 Super-K analysis old, but good data! K. McFarland, Neutrino Frontier

  15. MINOS 735km baseline 5.4kton Far Det. 1 kton Near Det. Running since early 2005 Precise measurement of nmdisappearance energy gives dm223 K. McFarland, Neutrino Frontier

  16. Two Mass Splitings: Three Generations figures courtesy B. Kayser • Oscillations have told us the splittings in m2, but nothing about the hierarchy • The electron neutrino potential (matter effects) can resolve this in oscillations, however. dmsol2 dm122≈8x10-5eV2dmatm2 dm232≈2.5x10-3eV2 K. McFarland, Neutrino Frontier

  17. Oases over the horizon? dmsol2 dm122≈8x10-5eV2dmatm2 dm232≈2.5x10-3eV2 Observation of A. deRujula at Neutrino 2000: If mass differences were not matched to… • Solar densities (small δm2) • the size of the earth (large δm2) … we would probably not have discovered neutrino oscillations Emboldened, neutrino physicists keep gambling… K. McFarland, Neutrino Frontier

  18. Three Generation Mixing slide courtesy D. Harris • Note the new mixing in middle, and the phase, d K. McFarland, Neutrino Frontier

  19. Two Paths for νμ→νe? LARGE SMALL LARGE SMALL • If “reactor” mixing, q13, is small, but not too small, there is an interesting possibility • At atmospheric L/E, dm232, q13 ne nm dm122, q12 K. McFarland, Neutrino Frontier

  20. Implication of two paths • Two amplitudes • If both small,but not too small, both can contribute ~ equally • Relative phase, d, between them can lead toCP violation (neutrinos and anti-neutrinos differ) in oscillations! • CP violation in leptons, along with Majorana masses, are key ingredients for leptogenesis of baryon asymmetry of Universe. dm232, q13 ne nm dm122, q12 K. McFarland, Neutrino Frontier

  21. q13in 2011: Not Zero! • T2K, an accelerator experiment, showed a signal of 6 events • 1.5 expected if q13=0 • Consistent, but less significant, indication from MINOS shortly after K. McFarland, Neutrino Frontier

  22. q13in 2012: Large! • Two reactor experiments recently showed overwhelming evidence for large q13. • Both place detectors near and far (~1km) from reactors • Look for a smallrate differencebetween twolocations K. McFarland, Neutrino Frontier

  23. q13in 2012: Daya Bay Figures from K. Heeger K. McFarland, Neutrino Frontier

  24. q13in 2012: RENO Figures from S.B. Kim K. McFarland, Neutrino Frontier

  25. Two paths! • Two amplitudes • Now we know the measurement of d and CP violation in oscillations is possible. • Bring on megaton detectors and multi-megawatt sources… • LBNE, Hyper-Kamiokande, LAGUNA, etc. dm232, q13 ne nm dm122, q12 K. McFarland, Neutrino Frontier

  26. Implications of Large q13 • If q13is large, then one of the two pathsis larger than the other. • This implies large signals, but small CP asymmetries dm232, q13 ne nm dm122, q12 K. McFarland, Neutrino Frontier

  27. Implications of Large q13 • Quantitative analysis to illustrate this expected behavior • Fractional asymmetry decreases as q13 increases • We live here • Statistics are (relatively) high, so the challenge will be controlling systematic uncertainties. K. McFarland, Neutrino Frontier

  28. NeutrinolessDouble Beta Decay • Signature of Majorananeutrino mass ~Now In progress F. Piquemal, Neutrino 2012 K. McFarland, Neutrino Frontier

  29. Foci for Current Work Johannes Blümer • Neutrinos as particles • Masses • Mixing and CP violation • Neutrinos as probes • Of the large • Of the small Stanford group, KAMLAND K. McFarland, Neutrino Frontier FNAL Visual Media Services

  30. Geoneutrinos • Radioactive decays in mantle contribute significantly to internal heating of earth • Neutrinos from these decays have been discovered • Weak evidence forexcess overamount fromcrust Stanford group, KAMLAND Steve Dye, Neutrino 2012 K. McFarland, Neutrino Frontier

  31. Ultra-High Energy Neutrinos • IceCube (km3 detector at south pole) has observed two events, likely 1000-10000 TeV neutrinos • Analysis is underway(note scale: “photoelectrons”) Johannes Blümer K. McFarland, Neutrino Frontier A. Ishihara, Neutrino 2012

  32. Neutrinos and Nucleons • MiniBooNE data sets have been an interesting challenge for this community. • In brief, models of nucleus effect on both initial and final state are probably too naïve. • Challenge is to develop workable models of these interactions to compare to data and use in oscillation measurements. Alcaraz et al, AIP Conf. Proc. 1189.145 (2009) K. McFarland, Neutrino Frontier

  33. Neutrino-Nucleon (cont’d) • New experiments (MINERvA, T2K, NOvA) will expand detector capabilities, energy range, number of nuclei studied and statistics over current data. • I.e., first results from MINERvA recently available • Small fraction of data on one target, preliminary and large systematics. Anti-neutrino CCQE on scintillator (CH) n candidate NuWro: T.Golan, C. Juszczak, J. Sobczyk. arXiv:1202.4197 candidate K. McFarland, Neutrino Frontier

  34. Conclusions • Nature hands us another gift: large q13 • New and bold, and potentially very long term, efforts to discover CP violation in neutrino oscillation. • Very challenging technically, and ambitious technically • Neutrinoless double beta decay still ungifted • Steady and hard-won progress towards sufficiently sensitive experiments. • Running and future experiments using neutrinos as probes solider on. • IceCube now at full size. Coming years could be exciting. • Low energy neutrino detection for geo-neutrinos, reactor monitoring is an exploding field. Many interesting proposals. • Neutrino-nucleus scattering physics should see a wealth of new data with MINERvA, T2K, NOvA detectors. The interplay between theory and experiment is familiar to those engaged in our main topic for this week. • Next new idea for harnessing neutrinos? K. McFarland, Neutrino Frontier

  35. Backup Superuminal More on CCQE K. McFarland, Neutrino Frontier

  36. Do Neutrinos Go Faster Than Light? • No K. McFarland, Neutrino Frontier

  37. Do Neutrinos Go Faster Than Light? • No K. McFarland, Neutrino Frontier

  38. Short-Range Correlations Recent Jlab studies of 12C quasi-elastic scattering have demonstrated significant probabilities to see multiple nucleons knocked out. [R. Subediet al., Science 320, 1476 (2008)] • Kinematics of interaction may be altered because scattering in nuclear environment occurs from a correlated pair ~20% of the time. • Not a new idea to apply toquasi-elastic scattering. Evidence in charged leptonscatteringnow strengthens the case. Dekker et al., PLB 266, 249 (1991) Singh, Oset, NP A542, 587 (1992) Gil et al., NP A627, 543 (1997) J. Marteau, NPPS 112, 203 (2002) Nieves et al., PRC 70, 055503 (2004) Martini et al., PRC 80, 065001 (2009) K. McFarland, Neutrino Interactions

  39. Explains MiniBooNE? Δσ Martini et al, PRC 81, 045502 (2010) • From the 12Cexperiment and calculations, expect a cross-section enhancement from correlated process: νμn→μ-p + νμ(np)corr.→μ-pp New work since Martini proposal Nieves et al., arXiv:1106.5374 [hep-ph] Bodeket al., arXiv:1106.0340 [hep-ph] Amaro, et al., arXiv:1104.5446 [nucl-th] Antonov, et al., arXiv:1104.0125 Benhar, et al., arXiv:1103.0987 [nucl-th] Meucci, et al., Phys. Rev. C83, 064614 (2011) Ankowski, et al., Phys. Rev. C83, 054616 (2011) Nieves, et al., Phys. Rev. C83, 045501 (2011) Amaro, et al., arXiv:1012.4265 [hep-ex] Alvarez-Ruso, arXiv:1012.3871[nucl-th] Benhar, arXiv:1012.2032 [nucl-th] Martinez, et al., Phys. LettB697, 477 (2011) Amaro, et al., Phys. Lett B696, 151 (2011) Martini, et al., Phys. RevC81, 045502 (2010) [compilation by G.P. Zeller] K. McFarland, Neutrino Interactions

  40. MINERvA Neutrino and Anti-Neutrino CCQE in Energy Bins Q2 distributions compared to GENIE, MA=0.99 GeV/c2 Low Energy, 2-4 GeV Similar trendsin Q2 in both beams, energies 20% of our data on CH High Energy, 4-10 GeV K. McFarland, Neutrino Interactions

More Related