1. Neutrino Oscillation Hitoshi Murayama (Berkeley) PRC-US Meeting @ IHEP June 12, 2006

2. Murayama, IHEP, June 12, 20062 Outline Past: Why Neutrinos? Present: Era of Revolution Future Conclusion

3. Past Why Neutrinos?

4. Murayama, IHEP, June 12, 20064 Interest in Neutrino Mass So much activity on neutrino mass already. Why am I interested in this? Window to (way) high energy scales beyond the Standard Model! Two ways: –Go to high energies –Study rare, tiny effects 

5. Murayama, IHEP, June 12, 20065 Rare Effects from High-Energies Effects of physics beyond the SM as effective operators Can be classified systematically (Weinberg)

6. Murayama, IHEP, June 12, 20066 Unique Role of Neutrino Mass Lowest order effect of physics at short distances Tiny effect (m /E ) 2 ~(0.1eV/GeV) 2 =10 –20 ! Interferometry (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

7. Murayama, IHEP, June 12, 20067 Ubiquitous Neutrinos They must have played some important role in the universe!

8. Present Era of Revolution

9. Murayama, IHEP, June 12, 20069 The Data Evidence for oscillation: “Indisputable” –Atmospheric –Solar –Reactor “strong” –Accelerator (K2K) And we shouldn’t forget: “unconfirmed” –Accelerator (LSND)

10. Murayama, IHEP, June 12, 200610 SuperKamiokande Atmospheric disappear Downwards  ’s don’t disappear 1/2 of upwards  ’s do disappear  2 /dof=839.7/755 (18%)  m 2 =2.5  10 -3 eV 2 sin 2 2  =1

11. Murayama, IHEP, June 12, 200611 SNO Solar transform in flavor 2/3 of e ’s  

12. Murayama, IHEP, June 12, 200612 KamLAND Reactor neutrinos do oscillate!  Proper time  L 0 =180 km

13. Murayama, IHEP, June 12, 200613 What we learned Lepton Flavor is not conserved Neutrinos have tiny mass, not very hierarchical Neutrinos mix a lot the first evidence for demise of the Minimal Standard Model Very different from quarks

14. Murayama, IHEP, June 12, 200614 Typical Theorists’ View ca. 1990 Solar neutrino solution must be small angle MSW solution because it’s cute Natural scale for  m 2 23 ~ 10–100 eV 2 because it is cosmologically interesting Angle  23 must be  23 ~ V cb =0.04 Atmospheric neutrino anomaly must go away because it needs a large angle Wrong!

15. Murayama, IHEP, June 12, 200615 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

16. Murayama, IHEP, June 12, 200616 Immediate Questions Dirac or Majorana? Absolute mass scale? How small is  13 ? CP Violation? Mass hierarchy? Is  23 maximal? LSND? Sterile neutrino(s)? CPT violation?

17. Future

18. Murayama, IHEP, June 12, 200618 Immediate Questions Dirac or Majorana? Absolute mass scale? How small is  13 ? CP Violation? Mass hierarchy? Is  23 maximal? LSND? Sterile neutrino(s)? CPT violation?

19. Murayama, IHEP, June 12, 200619 Immediate Questions Dirac or Majorana? Absolute mass scale? How small is  13 ? CP Violation? Mass hierarchy? Is  23 maximal? LSND? Sterile neutrino(s)? CPT violation?

20. Murayama, IHEP, June 12, 200620 LSND doesn’t fit into the picture Sterile neutrino (3+1) barely consistent with short-baseline data Sterile neutrinos are strongly constrained by WMAP+SDSS: m<0.26 eV (95%CL) (Seljak, Slosar, McDonald) CPT violation without sterile neutrino excluded by SNO+KamLAND HM, Pierce WMAP3yr+SDSS

21. Murayama, IHEP, June 12, 200621 The hell breaks loose Mini-BooNE will open the box this summer If Mini-BooNE confirms LSND, 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? 3+2? –Sterile neutrino and CPT violation? –Mass varying neutrinos? –Something even more wild and wacky?

22. Murayama, IHEP, June 12, 200622 What it would take 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

23. Murayama, IHEP, June 12, 200623 Immediate Questions Dirac or Majorana? Absolute mass scale? How small is  13 ? CP Violation? Mass hierarchy? Is  23 maximal? LSND? Sterile neutrino(s)? CPT violation?

24. Murayama, IHEP, June 12, 200624 T2K (Tokai to Kamioka)

25. Murayama, IHEP, June 12, 200625 Immediate Questions Dirac or Majorana? Absolute mass scale? How small is  13 ? CP Violation? Mass hierarchy? Is  23 maximal? LSND? Sterile neutrino(s)? CPT violation?

26. Murayama, IHEP, June 12, 200626 LMA confirmed by KamLAND Dream case for neutrino oscillation physics!  m 2 solar within reach of long-baseline expts Even CP violation may be probable Possible only if: –  m 12 2, s 12 large enough (LMA) –  13 large enough

27. Murayama, IHEP, June 12, 200627  13 decides the future The value of  13 crucial for the future of neutrino oscillation physics Determines the required facility/parameters/baseline/energy –sin 2 2  13 >0.01  conventional neutrino beam –sin 2 2  13 <0.01   storage ring,  beam Two paths to determine  13 –Long-baseline accelerator: T2K, NO A –Reactor neutrino experiment: 2  CHOOZ, Daya Bay

28. Murayama, IHEP, June 12, 200628 NO A Fermilab to Minnesota 32-plane block Admirer 25kt MINOS NO A L=810km

29. Murayama, IHEP, June 12, 200629 Daya Bay NPP Ling Ao NPP Ling Ao-ll NPP (under const.) Empty detectors: moved to underground halls through access tunnel. Filled detectors: swapped between underground halls via horizontal tunnels. Total tunnel length: ~2700 m 230 m 290 m 730 m 570 m 910 m Daya Bay Near 360 m from Daya Bay Overburden: 97 m Ling Ao Near 500 m from Ling Ao Overburden: 98 m Far site 1600 m from Ling Ao 2000 m from Daya Overburden: 350 m Mid site ~1000 m from Daya Overburden: 208 m Entrance portal Daya Bay

30. Murayama, IHEP, June 12, 200630 3  sensitivity on sin 2 2  13

31. Murayama, IHEP, June 12, 200631 T2K vs NO A LBL   e appearance Combination of –sin 2 2  13 –Matter effect –CP phase  95%CL resolution of mass hierarchy

32. Murayama, IHEP, June 12, 200632 Accelerator vs Reactor 90% CL Reactor w 100t (3 yrs) + Nova Nova only (3yr + 3yr) Reactor w 10t (3yrs) + Nova 90% CL McConnel & Shaevitz, hep-ex/0409028 90% CL Reactor w 100t (3 yrs) +T2K T2K (5yr, -only) Reactor w 10t (3 yrs) +T2K Reactor experiments can help in Resolving the  23 degeneracy (Example: sin 2 2  23 = 0.95 ± 0.01)

33. Murayama, IHEP, June 12, 200633 My prejudice Let’s not write a complicated theory The only natural measure for mixing angles is the group-theoretical invariant Haar measure Kolmogorov–Smirnov test: 64% sin 2 2  13 >0.04 (2  ) sin 2 2  13 >0.01 (99%CL)  23  12  13

34. Murayama, IHEP, June 12, 200634 Immediate Questions Dirac or Majorana? Absolute mass scale? How small is  13 ? CP Violation? Mass hierarchy? Is  23 maximal? LSND? Sterile neutrino(s)? CPT violation?

35. Murayama, IHEP, June 12, 200635 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

36. Murayama, IHEP, June 12, 200636 Seesaw Mechanism Why is neutrino mass so small? Need right-handed neutrinos to generate neutrino mass To obtain m 3 ~(  m 2 atm ) 1/2, m D ~m t, M 3 ~10 14 –10 14 GeV, but R SM neutral

37. 37 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)

38. Murayama, IHEP, June 12, 200638 Origin of Universe 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? ~ amplitude size of the universe R

39. Murayama, IHEP, June 12, 200639 LHC/ILC may help LHC finds SUSY ILC measures masses precisely If both gaugino and sfermion masses unify, there can’t be new particles < 10 14 GeV except for gauge-singlets

40. Murayama, IHEP, June 12, 200640 Plausible scenario 0  found LHC discovers SUSY ILC shows unification of gaugino and scalar masses Dark matter concordance between collider, cosmology, direct detection CP in -oscillation found Lepton flavor violation limits (  e ,  e conversion,  etc) improve Tevatron and EDM (e and n) exclude Electroweak Baryogenesis CMB B-mode polarization gives tensor mode r=0.16 If this happens, we will be led to believe seesaw+leptogenesis (Buckley, HM)

41. Murayama, IHEP, June 12, 200641 Conclusions Neutrino oscillation a unique tool to probe (very) high-energy world Era of revolution sin 2 2  13 decides the future My prejudice:  13 is “large” Reactor & accelerator LBL expts complementary To understand “big questions” we need a diverse set of experiments

42. Murayama, IHEP, June 12, 200642 The I visibles

43. Murayama, IHEP, June 12, 200643