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New Views on the Problem of CP Violation

H. Minakata Tokyo Metropolitan University (TMU). New Views on the Problem of CP Violation. Why do we look for leptonic CP violation?. Lepton-quark correspondence.

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New Views on the Problem of CP Violation

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  1. H. Minakata Tokyo Metropolitan University (TMU) New Views on the Problem of CP Violation

  2. Why do we look for leptonic CP violation? Neutrino Oscillation in Venice Hisakazu Minakata

  3. Lepton-quark correspondence • Quantum anomaly tells us that leptons and quarks are related with each other in a deeper level=> we want to know if leptonic KM phase is unsuppressed “lepton-quark correspondence” in the spirit of Nagoya model (Sakata et al., ‘60th) Shoichi Sakata Neutrino Oscillation in Venice Hisakazu Minakata

  4. Leptogenesis • Lepton # asymmetry generated by Majorana n converted to baryon # asym. by “spharelon” • => standard model for baryogenesis? • Need CP violating phases • Related with leptonic KM phase d ? (Buchmuller et al.) (Fukugita-Yanagida ‘86) Neutrino Oscillation in Venice Hisakazu Minakata

  5. Good old way Neutrino Oscillation in Venice Hisakazu Minakata

  6. Good-old way of measuring CPV P(nm->ne) = P P(nmbar->nebar) = CP[P] DP =P - CP[P] = nonzero gives you CP violation N. Cabibbo … A useful tool for --> representation: Bi-probability plot H.M. & H. Nunokawa (=MN), JHEP 10 (2001) 001 Neutrino Oscillation in Venice Hisakazu Minakata

  7. DP =P - CP[P] = P(nm->ne;Dm2, d, a) -P(nmbar->nebar; Dm2, d, a) = P(nm->ne;Dm2, d, a) - P(nm->ne;- Dm2, p-d, a) If P is insensitive to d => = P(nm->ne;Dm2) - P(nm->ne;-Dm2) = Dm2-odd DP measures sign of Dm2 in d-insensitive region DP measures d in matter-insensitive region DP =P - CP[P]; sign of Dm2 or CPV? = P(nm->ne;Dm2, -d, -a) = P(nm->ne;- Dm2, p-d, a) (if Dm2solar /Dm2atm << 1) Low-E superbeam;MN, Sato, Richter, … Neutrino Oscillation in Venice Hisakazu Minakata

  8. TV; Cleanest way of measuring CPV P(nm->ne)=P P(ne->nm)=T[P] DPT =P - T[P] gives you T (=CP under CPT) violation P = Acosd + Bsind + C T[P] = Acosd - Bsind + C DPT =P - T[P] = 2 Bsind If d = 0 => DPT = 0 Experimentally, it is NOT easy => beta beam! MN-Parke, hep-ph/0204171 Neutrino Oscillation in Venice Hisakazu Minakata

  9. New ways Neutrino Oscillation in Venice Hisakazu Minakata

  10. New ways of measuring CPV? Reactor-LBL combination BNL strategy with several oscillation maxima (neutrino only) Its low-energy version? Neutrino Oscillation in Venice Hisakazu Minakata

  11. Reactor measurement of q13 • Independent of d, matter effect, q23, q12, solar Dm2 => Pure measurement of q13 ne disappearance probability (H.M. Sugiyama, Yasuda, Inoue, Suekane, hep-ph/0211111) Neutrino Oscillation in Venice Hisakazu Minakata

  12. Reactor-LBL combination Principle very simple ! => ne appearance at OM + reactor q13 measurement gives you d • JPARC-HK neutrino mode, 2 years (4 MW & 540 kton, s/bg accounted) • 50 ton detectors @Kashiwazaki-Kariwa NPP, 1-10 years • CP violation can be detected by reactor-LBL combination ! (H.M. H.Sugiyama, hep-ph/0309323 v2 -> PLB) Neutrino Oscillation in Venice Hisakazu Minakata

  13. Detecting CPV by reactor-LBL combination; details Realistic sdb crucial in sensitivity estimate in phase II Neutrino Oscillation in Venice Hisakazu Minakata

  14. Can Super-K Do the Job? In the case of “C-evaluation” by the HK review committee • JPARC-SK neutrino mode, 10 years (0.75 MW & 22.5 kton, s/bg accounted) • 50 ton detectors @Kashiwazaki-Kariwa NPP, 1-10 years • Though less sensitive, SK can do a job ! the only way to detect CPV without HK? Neutrino Oscillation in Venice Hisakazu Minakata

  15. We must know sign of Dm2 in advance, otherwise … This is nothing but Parameter Degeneracy due to sign (Dm2)! MN, JHEP 10 (2001) 001 Neutrino Oscillation in Venice Hisakazu Minakata

  16. Why so much ambiguity by sign-Dm2 degeneracy? The reason is: • Large d2 - d1 (= p/2 ~ p) in overlapping region of different-sign Dm2 ==> • CPC-CPV confusion Neutrino Oscillation in Venice Hisakazu Minakata

  17. BNL strategy (hep-ex/0211001) Neutrino Oscillation in Venice Hisakazu Minakata

  18. <=background ? JPARC-HK vs. BNL proposal 1 s • L=295 km/E=0.7 GeV vs. L=2540 km/E=0.5-5GeV ==> 1st oscillation maximum vs. 1st-3rd oscillation max. • Clean environment for CPV vs. exploring oscillation pattern, sign of Dm213, can prove solar Dm2, can run with only nm Neutrino Oscillation in Venice Hisakazu Minakata

  19. Low-energy version of BNL strategy? • JPARC accelerator complex funded =>we will have low-energy neutrino superbeam • Low-energy beam cannot see 2nd OM because of Fermi motion • Depend on Dm2 L/2E => p, 3p means the detectors placed at L and 3L => • 300 km: Kamioka • 900 km: Seoul, Korea! Similar to 2-detector strategy in: MN hep-ph/9706281 Neutrino Oscillation in Venice Hisakazu Minakata

  20. Shooting Korea Neutrino Oscillation in Venice Hisakazu Minakata

  21. Bi-probability plot for JPARC-Korea • Korean detector more important for accurate determination of d (steeper slope) • It is hard to determine sign(Dm2) from neutrino run only • Mathematically, there is no degeneracy apart from d -> p - d (similar to KMN) MN to appear => Neutrino Oscillation in Venice Hisakazu Minakata

  22. n-antin run at the oscillation maximum (reminder) In the thinnest ellipse limit (KMN) • There is no degeneracy apart from d -> p - d • sin22qis the “distance to the origin” Kajita-MN, hep-ph/0112345 Neutrino Oscillation in Venice Hisakazu Minakata

  23. Conclusion • Real alternative togood-old n-antin low-E superbeamdoes not appear to show up yet • Reactor-LBL may work but confidence level less than 2 s even with Hyper-K • BNL strategy interesting to explore but CP sensitivity less than 1 s=> very long-baseline setting loses statistics (in conventional beams) • Need to determine sign Dm2,otherwise CPV-CPC confusion <= the only way to detect CPV without HK? Low-E version exists but expensive Neutrino Oscillation in Venice Hisakazu Minakata

  24. LBL measurement of q13 Very simple form ! Very simple form! JPARC-SK q13 sensitivity; OA2°, 5 years Neutrino Oscillation in Venice Hisakazu Minakata

  25. Reactor-LBL complementarity I • Pure measurement of q13 by reactors help resolve (q23 --> p/2-q23) degeneracy • If lucky, one may see CP & mass hierarchy (H.M. Sugiyama, Yasuda, Inoue, Suekane, hep-ph/0211111) Neutrino Oscillation in Venice Hisakazu Minakata

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