1. LBL neutrinos; looking forward to the future Hisakazu Minakata Tokyo Metropolitan University

2. September 14, 2009Ustron09 oscillation has been clearly seen! K2K SK MINOS 07 KamLAND 08

3. September 14, 2009Ustron09 Exploring the unknowns; 1-3 sector and mass hierarchy  =U  i i SK-atm+K2K+MINOS solar+KamLAND Atm + accel  => <= solar + reactor

4. September 14, 2009Ustron09 Next generation experiments 260m high Mt. 88m high Mt.

5. September 14, 2009Ustron09 Foreseeing the next step

6. Next step? Proof of validity of lepton KM mechanism in mass embedded SM Indicate quark-lepton unity/correspondence vacuum environment cleaner, but doable in matter Conventional vs. unconventional mass pattern of neutrinos Probe physics of neutrino mass matter effect required to resolve the mass hierarchy September 14, 2009Ustron09 CP violationMass hierarchy

7. September 14, 2009Ustron09 Terminology; degeneracy & bi-P plot

8. September 14, 2009Ustron09 A machinery in my talk Oscillation probability draw ellipse if plotted in bi-P plane Role played by CP phase  and the matter clearly distinguished Art work by Adam Para Two solutions of S 23 2 x HM-Nunokawa JHEP01

9. September 14, 2009Ustron09 Cause of the degeneracy; easy to understand You can draw two ellipses from a point in P-Pbar space Intrinsic degeneracy Doubled by the unknown sign of  m 2 4-fold degeneracy

10. Origin of sign-  m 2 degeneracy P  e in vacuum has an approximate invariance under the transformation It ensures the degree of freedom of sign-  m 2 flipped solution Continuity in change in matter effect guarantees its existence generically in matter September 14, 2009Ustron09 MN JHEP01

11. September 14, 2009Ustron09 Various options/pos sibilities

12. September 14, 2009 Ustron09 Strategy for both CP and MH Neutrino oscillation probability is a function of L/E in vacuum In matter, matter effect comes in via a different way, aL =\sqrt{2}G F N e L There are two ways to explore structure of oscillation => mixing parameters used by BNL-type multi-OM approach (also used in off-axis beam) 2 detector approach Vary E Vary L

13. September 14, 2009Ustron09 BNL strategy (hep-ex/0211001)

14. September 14, 2009Ustron09 Project X: Off-axis NOVA --> VLBL multi-OM type approach

15. September 14, 2009 Ustron09 Perspectives (mainly) in the North East Asia

16. T2K (Tokai-to-Kamioka) 2 nd phase and CERN-MEMPHYS September 14, 2009Ustron09 CP violation measurement at low E and short L=best place for looking for CP violation (low E superbeam, HM-Nunokawa 00) 4 MW + 1 megaton water Cherenkov Mass hierarchy difficult to resolve

17. September 14, 2009Ustron09 Lepton CP sensitivity at T2K thick: 3 , thin: 2  Sensitivity to CPV at T2K is roughly comparable to T2KK, a more aggressive setting T2KKT2K

18. September 14, 2009Ustron09 More ambitious approaches

19. J-PARC beam at Tokai September 14, 2009Ustron09

20. 2.5 degrees off-axis beam @ Kamioka L=1000 km OA1.5 OA1.0 L=1100 km Rubbia@ T2KK WS September 14, 2009Ustron09

21. 658km 0.8deg. Off-axisシナリオ２ δ=0° ν e Spectrum Beam ν e Background CP Measurement Potential NP08, arXiv:0804.2111 δ=90° δ=180°δ=270° sin 2 2θ 13 =0.03,Normal Hierarchy 33 100kton Lq. Ar TPC @ 658km beam only. 1.66 MW sin 2 2  13  A.Rubbia et al. presented by T. Nakaya, June09 Okinoshima A J-PARC version of BNL strategy

22. September 14, 2009Ustron09 What’s good in T2KK?

23. September 14, 2009Ustron09 T2KK=Tokai-to-Kamioka-Korea Why don’t you bring one of the 2 tanks to Korea? (@EPP2010)

24. September 14, 2009Ustron09 Original idea: sensitive because dynamism in 2nd oscillation maximum Ishitsuka-Kajita-HM- Nunokawa 05

25. September 14, 2009Ustron09 Two detector method is powerful

26. September 14, 2009Ustron09 Spectral information solves intrinsic degeneracy from 1000 page Ishitsuka file SK momentum resolution ~30 MeV at 1 GeV T2K T2KK 2 detector method powerful! Ishitsuka-Kajita-HM- Nunokawa 05

27. September 14, 2009Ustron09 Two-detector setting is powerful With the same input parameter and Korean detector of 0.54 Mt the sign-  m 2 degeneracy is NOT completely resolved T2KK Korea only

28. Latest development September 14, 2009Ustron09 F. Dufour, T. Kajita, E. Kearns, K. Okumura, to appear Another realization of BNL strategy (see also Hagiwara et al.)

29. Sensitivity to CP and MH September 14, 2009Ustron09 5 + 5 years neutrino anti-neutrino running with 1.66 MW beam (10 ∗ 2.59×10 21 POT) with 40GeV protons, 2 x 0.27Mton(FV) detector.

30. CP fraction plot September 14, 2009Ustron09 F. Dufour, T. Kajita, E. Kearns, K. Okumura, to appear

31. September 14, 2009Ustron09 Robustness matters

32. September 14, 2009 Ustron09 Relative cross section error does matter Identical 2 detector setting robust to larger systematic error It gives conservative lower bounds on sensitivity estimate of mass hierarchy and CP Barger et al. 07 T2K II T2KK

33. September 14, 2009Ustron09 Another issue; matter density profile

34. Large  13 perturbation theory of oscillation September 14, 2009Ustron09 We take the last one, large  13 just below Chooz limit

35. Large  13 perturbation theory (continued) September 14, 2009Ustron09 ~  1/2 ~  1 ~  2 ~  3/2

36. Matter density variation September 14, 2009Ustron09 asymmetric baseline

37. T violation September 14, 2009Ustron09 50% correction to the main term if Im(r n ) ~ r 0 for L=1000 km, E=2 GeV,  =2.8 g/cm 3, s 13 =0.17, etc. => confuse T violation See also Akhmedov et al.01

38. September 14, 2009Ustron09 Conclusion Some perspectives of future LBL experiments for CP and mass hierarchy are reviewed with an emphasize of North- East Asian perspective Emphasis placed on “principle” than numerical results Robustness issues addressed Large  13 perturbation theory is formulated to address uncertainty in matter density profile issue of asymmetric profile