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What is the case for nufact?

What is the case for nufact?. Hitoshi Murayama (UC Berkeley) Intl Scoping Study Meeting of Nufact and Superbeam Boston University, March 8, 2006. The Question. Neutrino physics has been full of surprises We’ve learned a lot in the last ~8 years We want to learn more

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What is the case for nufact?

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  1. What is the case for nufact? Hitoshi Murayama (UC Berkeley) Intl Scoping Study Meeting of Nufact and Superbeam Boston University, March 8, 2006

  2. The Question • Neutrino physics has been full of surprises • We’ve learned a lot in the last ~8 years • We want to learn more • New projects are more and more expensive • Is it really worth it? • Especially worth ~B$, B€, 100B¥? ISS Physics WS Boston

  3. Elevator Pitch • If you happen to be on an elevator with a powerful senator, can you explain why you want to spend ~B$ on your project in 30 seconds? ISS Physics WS Boston

  4. What will NOT work For politicians and taxpayers, these arguments wouldn’t be convincing and/or interesting enough • Measurements as precisely as we can • Push limits on 13 as much as we can • Verify the three-generation framework of neutrino oscillation • Distinguish different flavor modles • Field needs another machine to sustain itself ISS Physics WS Boston

  5. Quantum Universe Report What are neutrinos telling us? • Of all the known particles, neutrinos are the most mysterious. They played an essential role in the evolution of the universe, and their tiny nonzero mass may signal new physics at very high energies. ISS Physics WS Boston

  6. Quantum Universe Report • Einstein’s Dream of Unified Forces • Are there undiscovered principles of nature: new symmetries, new physical laws? • How can we solve the mystery of dark energy? • Are there extra dimensions of space • Do all the forces become one? • The Particle World • Why are there so many kinds of particles? • What is dark matter? How can we make it in the laboratory? • What are neutrinos telling us? • The Birth of the Universe • How did the universe come to be? • What happened to the antimatter? ISS Physics WS Boston

  7. Outline • Why Neutrinos? • A few scenarios • sin2 213≪ 0.01 • sin2 213 > 0.01 • Mini-BooNE confirms LSND • LHC discovers new physics < TeV • The Big Questions • Scenario to “establish” seesaw/leptogenesis • Conclusion ISS Physics WS Boston

  8. Why Neutrinos?

  9. Interest in Neutrino Mass • So much activity on neutrino mass already. Why are we doing this? Window to (way) high energy scales beyond the Standard Model! ISS Physics WS Boston

  10. Why Beyond the Standard Model • Standard Model is sooooo successful. But none of us are satisfied with the SM. Why? • Because it leaves so many great questions unanswered  Drive to go beyond the Standard Model • Two ways: • Go to high energies • Study rare, tiny effects  ISS Physics WS Boston

  11. Rare Effects from High-Energies • Effects of physics beyond the SM as effective operators • Can be classified systematically (Weinberg) ISS Physics WS Boston

  12. Unique Role of Neutrino Mass • Lowest order effect of physics at short distances • Tiny effect (mn/En)2~(0.1eV/GeV)2=10–20! • Inteferometry (i.e., Michaelson-Morley) • Need coherent source • Need interference (i.e., large mixing angles) • Need long baseline Nature was kind to provide all of them! • “neutrino interferometry” (a.k.a. neutrino oscillation) a unique tool to study physics at very high scales ISS Physics WS Boston

  13. Ubiquitous Neutrinos They must have played some important role in the universe! ISS Physics WS Boston

  14. The Data de Gouvêa’s classification: • “Indisputable” • Atmospheric • Solar • Reactor • “strong” • Accelerator (K2K) And we shouldn’t forget: • “unconfirmed” • Accelerator (LSND) ISS Physics WS Boston

  15. Historic Era in Neutrino Physics We learned: • Atmospheric nms are lost. P=4.2 10–26(SK) (1998) • converted most likely to nt (2000) • Solar ne is converted to either nm or nt(SNO) (2002) • Only the LMA solution left for solar neutrinos (Homestake+Gallium+SK+SNO) (2002) • Reactor anti-ne disappear (2002) and reappear (KamLAND) (2004) ISS Physics WS Boston

  16. Neutrinos do oscillate! Proper time  ISS Physics WS Boston

  17. What we learned • Lepton Flavor is not conserved • Neutrinos have tiny mass, not very hierarchical • Neutrinos mix a lot the first evidence for incompleteness of Minimal Standard Model Very different from quarks ISS Physics WS Boston

  18. Typical Theorists’ View ca. 1990 • Solar neutrino solution must be small angle MSW solution because it’s cute • Natural scale for Dm223 ~ 10–100 eV2 because it is cosmologically interesting • Angle q23 must be ~ Vcb =0.04 • Atmospheric neutrino anomaly must go away because it needs a large angle Wrong! Wrong! Wrong! Wrong! ISS Physics WS Boston

  19. The Ivisibles ISS Physics WS Boston

  20. ISS Physics WS Boston

  21. The Big Questions • What is the origin of neutrino mass? • Did neutrinos play a role in our existence? • Did neutrinos play a role in forming galaxies? • Did neutrinos play a role in birth of the universe? • Are neutrinos telling us something about unification of matter and/or forces? • Will neutrinos give us more surprises? Big questions  tough questions to answer ISS Physics WS Boston

  22. Immediate Questions • Dirac or Majorana? • Absolute mass scale? • How small is q13? • CP Violation? • Mass hierarchy? • Is q13 maximal? • LSND? Sterile neutrino(s)? CPT violation? ISS Physics WS Boston

  23. Tools • Available tools now: • SuperK, SNO, KamLAND, Borexino, Mini-BooNE, MINOS, Cuoricino, NEMO, SDSS, … • Available soon (?): • Opera, Double-Chooz, T2K, MINERA, SciBooNE, NOA, reactor 13 expts, KATRIN, PLANCK, new photometric surveys, more 0 expts, … Do we really need more? What do we need? ISS Physics WS Boston

  24. Do we really need more?What do we need? • The answer depends on what we will find in the near future • Talk about a few scenarios • sin2 213≪ 0.01 • sin2 213 > 0.01 • Mini-BooNE confirms LSND • LHC discovers new physics < TeV ISS Physics WS Boston

  25. sin2 213≪0.01

  26. Obvious case? • Superbeams will not address 13, mass hierarchy, or CP violation • A clear case for neutrino factory and/or -beam • de Gouvêa: Will we get the funds to get a neutrino factory even if all previous investments end up “unsuccessful”? ISS Physics WS Boston

  27. sin2 213>0.01

  28. sin2 213>0.01 • Reactor/T2K/NOA finds sin2 213 This is my prejudice • Upgrades (4MW J-PARC to HyperK, Proton Driver+NOA 2nd detector, etc) • Measures sin2 213 precisely • Determines mass hierarchy • Discovers CP violation What’s left then? ISS Physics WS Boston

  29. The source of CP violation • Having seen does not tell us what is causing it (in particular in the presence of “matter effect background”) • Is it due to the Dirac phase in the MNS matrix? • Exactly the same question being addressed by B-factories • i.e., K can be explained by the KM phase, but is it? • Cross check in a different system, e.g., B  Yes! • Is there new interaction (e.g. SUSY loop)?  future ISS Physics WS Boston

  30. Testing MNS hypothesis • One way I know is to use tau modes • Consequence of CPT and three flavors • Can they be studied at neutrino factory? • I know it is tough even for a neutrino factory, but other facilities will clearly not do it ISS Physics WS Boston

  31. () () (e) (e) Testing MNS hypothesis • A simulation like this will make the case w/o new neutrino interaction with new neutrino interaction ISS Physics WS Boston

  32. Mini-BooNE confirms LSND

  33. The hell breaks loose • In this case, it is hard to understand what is going on, because there is currently no simple way to accommodate LSND result with other neutrino data • Multiple sterile neutrinos? • Sterile neutrino and CPT violation? • Mass varying neutrinos? • Something even more wild and wacky? ISS Physics WS Boston

  34. What it takes • We will need neutrino “oscillation” experiments with multiple baselines, multiple modes • E~10 GeV, L~10km, looking for  appearance • Redo CDHSW ( disappearance experiment with L=130 & 885m, E=19.2GeV) • E~1 GeV, L~1 km, looking for oscillatory behavior and CP violation in e, or better, e • Some in the air, some in the earth • Probably more • Muon source would help greatly ISS Physics WS Boston

  35. LHC discovers new physics <TeV

  36. TeV new physics • Whatever it is, • SUSY, large extra dimensions, warped extra dimension, technicolor, Higgsless, little Higgs it is hard to avoid the TeV-scale physics to contribute to flavor-changing effects in general • Renewed strong case for, e.g., super-B • Very strong case for lepton flavor violation, g2 • Hence, for a muon storage ring • Obvious competition with ILC and beyond ISS Physics WS Boston

  37. For example, SUSY • High-energy data (LHC/ILC) will provide masses of superparticles • But most likely not their mixings • Low-energy LFV experiments (e.g., e, AeA) provide rates (T-odd asymmetry if lucky) • Combination of virtual particles in the loop and their mixing • Put them together • Resolve the mixing • Constrain models of flavor ISS Physics WS Boston

  38. What about the Big Questions? • What is the origin of neutrino mass? • Did neutrinos play a role in our existence? • Did neutrinos play a role in forming galaxies? • Did neutrinos play a role in birth of the universe? • Are neutrinos telling us something about unification of matter and/or forces? • Will neutrinos give us more surprises? Big questions  tough questions to answer ISS Physics WS Boston

  39. Origin of Neutrino Mass,our existence, even our universe

  40. Neutrinos must be Massless • All neutrinos left-handed  massless • If they have mass, can’t go at speed of light. • Now neutrino right-handed??  contradiction  can’t be massive ISS Physics WS Boston

  41. (1) Dirac Neutrinos: There are new particles, right-handed neutrinos, after all Why haven’t we seen them? Right-handed neutrino must be very very weakly coupled Why? Two ways to go ISS Physics WS Boston

  42. Extra Dimensions • All charged particles are on a 3-brane • Right-handed neutrinos SM gauge singlet  Can propagate in the “bulk” • Makes neutrino mass small mn ~ 1/R if one extra dim  R~10mm • An infinite tower of sterile neutrinos • Or anomaly mediated SUSY breaking ISS Physics WS Boston

  43. (2) Majorana Neutrinos: There are no new light particles Why if I pass a neutrino and look back? Must be right-handed anti-neutrinos No fundamental distinction between neutrinos and anti-neutrinos! Two ways to go ISS Physics WS Boston

  44. Seesaw Mechanism • Why is neutrino mass so small? • Need right-handed neutrinos to generate neutrino mass , but nR SM neutral To obtain m3~(Dm2atm)1/2, mD~mt, M3~1015GeV (GUT!) ISS Physics WS Boston

  45. electromagnetic, weak, and strong forces have very different strengths But their strengths become the same at 1016 GeV if supersymmetry To obtain m3~(Dm2atm)1/2, mD~mt  M3~1015GeV! Grand Unification M3 Neutrino mass may be probing unification: Einstein’s dream ISS Physics WS Boston

  46. Leptogenesis • You generate Lepton Asymmetry first. (Fukugita, Yanagida) • Generate L from the direct CP violation in right-handed neutrino decay • L gets converted to B via EW anomaly  More matter than anti-matter  We have survived “The Great Annihilation” • Despite detailed information on neutrino masses, it still works (e.g., Bari, Buchmüller, Plümacher) ISS Physics WS Boston

  47. Maybe an even bigger role: inflation Need a spinless field that slowly rolls down the potential oscillates around it minimum decays to produce a thermal bath The superpartner of right-handed neutrino fits the bill When it decays, it produces the lepton asymmetry at the same time (HM, Suzuki, Yanagida, Yokoyama) Decay products: supersymmetry and hence dark matter Neutrino is mother of the Universe? ~ R Origin of Universe amplitude size of the universe ISS Physics WS Boston

  48. Origin of the Universe • Right-handed scalar neutrino: V=m2f2 • ns=0.96 • r=0.16 • Detection possible in the near future ISS Physics WS Boston

  49. Can we prove it experimentally? • Unfortunately, no: it is difficult to reconstruct relevant CP-violating phases from neutrino data • But: we will probably believe it if the following scenario happens Archeological evidences ISS Physics WS Boston

  50. A scenario to “establish” seesaw • We find CP violation in neutrino oscillation • At least proves that CP is violated in the lepton sector • Ue3 is not too small • At least makes it plausible that CP asymmetry in right-handed neutrino decay is not unnaturally suppressed • But this is not all ISS Physics WS Boston

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