Do Neutrinos Violate CP?

1. Do Neutrinos Violate CP? Hisakazu Minakata Tokyo Metropolitan University

2. Do neutrinos violate CP? Tough question! • I believe the answer YES, • Because MNS matrix is S+(l)S(); it is hard to believe that they all cancel out => next sheet • Possibility of cancellation? • accidentally small 13 vs. accidentally small  • small 13 may arise if there is a symmetry, but no symmetry is known for tuned small  Nishikawa-san may be right … NOVE06@Venice

3. Do neutrinos violate CP? (continued) • Therefore, absence of KM type CPV highly unlikely • What is nontrivial, however, is to understand the meaning of  when it is measured • requires interdisciplinary knowledge, e.g., large mixing in susy sectors, LFV, leptogenesis, KM phase, etc NOVE06@Venice

4. How about Majorana CPV? • There is a strong argument due to Yanagida-san, which answers the question in the positive • We know that our universe is asymmetric to baryon number • We know that above 1 TeV only meaningful quantum number is B-L, not B or L separately, because of anomaly (“sphaleron”) • Therefore, we must have B+L generation to have nonzero baryon number NOVE06@Venice

5. How about Majorana CPV? (continued) • Let us assume SM of particle physics => no operator which violates B+L • The lowest dimension operator which violate B-L is which must exists • This is nothing but the neutrino mass operator observed by SK, SNO, KamLAND, and K2K, and others (confirmed to exists!) • Therefore,  Majorana mass must exist (otherwise, we do not have baryon # excess) NOVE06@Venice

6. Rest of my talk • Comments on how to measure CPV • Issue of two (can be naturally) small quantities, 13,deviation from max 23 : • 13 revisited • 23 revisited NOVE06@Venice

7. How can CPV be probed? NOVE06@Venice

8. How can CPV be probed? • Low-energy superbeamvs. high-energy  factory • Low-energy because CPV is large • High-energy because muon detection is clean • Now, both approaches start to converge! JJ.Gomez-Cadenas (private), Brondel (Nufact-ISS2@KEK) NOVE06@Venice

9. How CP phase  affects oscillation probability? At low energy  changes probability in a dynamic way and in a different way from matter Seen clearly by bi-probability plot Art work by Adam Para => Two solutions of S232 x NOVE06@Venice

10. For experts Spectral information powerful • Intrinsic degeneracy nearly resolved by T2K II setting even at small 13 • Yet, sign-m2 (mass hierarchy) degeneracy is robust Ishitsuka et al. NOVE06@Venice

11. 2 detector method for CPV HM-H.Nunokawa, 97 • Since  oscillation is a phase-modulated phenomenon, the distance-dependent information is important • Particularly powerful for 2nd baseline at ~ 2nd oscillation maximum => Kajita-san’s talk for more about it NOVE06@Venice

12. NOVE03; birthplace of Kamioka-Korea strategy (my story) NOVE06@Venice

13. How big is 13?; the crucial question NOVE06@Venice

14. Vanishing 13; ‘t Hooft approved If  symmetry is the case … near maximal 23 small 23 Grimus, Ma, Valle … (infinite references) NOVE06@Venice

15. There are 2 ways to answer the question LBL vs. reactor NOVE06@Venice

16. New possibility! => Messbauer enhanced e-bar B decay+resonant absorption Raghavan, hep-ph/0511191, hep-ph/0601079 • e-bar+3He+bound-e -> 3H; resonant nature • Monochromatic (18.6keV) e-bar beam from inverse reaction; 3H bound state  decay • Recoilless setting by embedding 3H and 3He into solid => Messbauer effect 10 m baseline 13 experiment ! NOVE06@Venice

17. Rate estimate =1132 s Doppler shift • res = 4.2 x 10-41 [4 (a Z)3] (E e-bar /MeV)/ft 1.2 x 10-5 106/(FDHM) =107 = 10-42 cm2 (capture cross section) • R = f NTres = 0.03/day (100 MCi, 1kg 3He) • T2 ~ 2 ms =>  = 3 x 10-13 relativeenhancement by a factor of ~ 1012 (x0.07) • res = 10-31 cm2 (11 order enhancement) • R = 3 x 106 /day (1 MCi, 100g 3He, L=10m) Messbauer enhancement million events a day! E/E ~ 10-17 => neutrino’s gravitational red shift NOVE06@Venice

18. Which kind of 13 experiment? • Spectrum analysis requires multiple detector or movable detector possible because L=10 m • Reduction of systematic error => 0.1-0.3% if direct counting of 3H atom possible • Monochromatic beam + gigantic statistices => high sensitivity not only to 13 but also tom2 NOVE06@Venice

19. Sensitivities to m2 and sin2213 sin2213 = 0.1 sin2213 = 0.01 • Run IIB = 10 point measurement at LOM/5, 3LOM/5, … 19LOM/5, • each 106 events, usys = 0.2%, c = 10% NOVE06@Venice

20. Sensitivities to m2 and sin2213 1DOF, optimistic error: usys=0.2% HM & S. Uchinami, hep-ph/0602046 NOVE06@Venice

21. Sensitivities to m2 and sin2213 1DOF, pessimistic error: usys=1% NOVE06@Venice

22.  mass hierarchy by m2(ee) - m2() Nunokawa et al. 05 NOVE06@Venice

23. Are there ways to solve 23 degeneracy? NOVE06@Venice

24. Reactor + accelerator method • A-disappearance => s223=0.4 or 0.6 • A-appearance => s223sin2213 = 0.06 • R => sin2213 = 0.1 • Solves 23 degeneracy MSYIS, hep-ph/0211111 NOVE06@Venice

25. Region of resolved 23 degeneracy T2K II (4MW+HK) + phase II type reactor; Hiraide et al. (7 Samurai), hep-ph/0601258 MSYIS => NOVE06@Venice

26. Atm ; best way for 23 degeneracy? T.Kajita@NNN05 NOVE06@Venice

27. n3 n2 n1 sin2q13 sin2q23 Kajita@Korean detector WS 0.092 Mtonyr Super-K data cosqzenith Analysis with and w/o solar terms Search for non-zero q13 En(GeV) with 12 terns (best fit s2q23 = 0.51) w/o 12 NOVE06@Venice

28. Conclusion • Leptonic CPV, both KM and Majorana types, very likely to exist • There are still rooms in making progress with ‘‘known conventional beam’’ for exploring CPV • New opportunities exist in Messbauer enhanced recoilless resonant absorption • 23 degeneracy; hardest problem for accelerator (reactor or atmospheric?) NOVE06@Venice