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Exploring the Impact of Large Q13 on Future Neutrino Oscillation Experiments

Delve into the implications of large Q13 for strategies in neutrino oscillation experiments, CP violation studies, and mass hierarchy resolutions. Discover the physics behind this phenomenon and potential paths for robust discoveries and precise measurements.

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Exploring the Impact of Large Q13 on Future Neutrino Oscillation Experiments

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  1. If q13 is large, then what ? Hisakazu Minakata Tokyo Metropolitan University

  2. Title too timely? Yes, but meant to be a speculative one when proposed Nufact2011@CERN-UNIGE

  3. Apparently q13 is large 6 events at T2K ! Released in June 15@KEK Nufact2011@CERN-UNIGE

  4. T2K appearance event distribution Nufact2011@CERN-UNIGE

  5. MINOS also saw excess Nufact2011@CERN-UNIGE

  6. Global analysis Fogli et al. June 29 • All n experiments coherently support q13 ~ 8 degree Nufact2011@CERN-UNIGE

  7. We will soon hear more about this from reactors! Nufact2011@CERN-UNIGE

  8. There are two issues (at least) Nufact2011@CERN-UNIGE

  9. Two issues of large q13 • What is the influence of large q13 on strategies of future n oscillation experiments ? • What the large q13 means? Physics behind the large q13 Smirnov’s talk Mohapatra’s talk … Nufact2011@CERN-UNIGE

  10. Wide possibilities are now open for CP • Conventional nmsuperbeam can do a much better job for CP (and possibly for mass hierarchy) than it was thought • This means that we should reconsider about strategy for CP • I believe megaton-scale water Cherenkov / 100 kt liquid Ar is still needed for robust discovery of CPV • Yet, the paths to go there could have more variety “guerrilla type” approaches possible Nufact2011@CERN-UNIGE

  11. Various options become possible for CP Nufact2011@CERN-UNIGE

  12. Reactor accelerator combination HM-Sugiyama 04 Huber et al. 09 Nufact2011@CERN-UNIGE

  13. n + n-bar combination in NOnA / T2K NOVA@wine&cheese June17 Nufact2011@CERN-UNIGE

  14. Reactor-accelerator & n+n-bar methods • Apparently the methods works, but unlikely to cover all the d space • Quantitative estimation of CP sensitivity required very interesting !! • Results of CP sensitivity studies indicate the importance of mass hierarchy resolution Nufact2011@CERN-UNIGE

  15. Various options possible… MEMPHYS: Dashed line = combining SPL + beta Campagne et al. 07 Nufact2011@CERN-UNIGE

  16. What do you propose? Nufact2011@CERN-UNIGE

  17. Opening the possibility of “all in one” • With large q13 ~ Chooz limit a megaton scale water Cherenkov can do many • With intense n and n-bar beam it can measure d • With gigantic atmospheric n events it could determine mass hierarchy • in situ measurement of everything in a single detector • It can do proton decay • It can do many astrophysics too Kakuno-san’s talk water Cherenkov vs. liquid Ar vs. TASD debatable Nufact2011@CERN-UNIGE

  18. Issues in precision measurement of CP Nufact2011@CERN-UNIGE

  19. megaton class detectors (examples) T2K II MEMPHYS Nufact2011@CERN-UNIGE

  20. CP sensitivity is not maximal at sin2q13=0.1 MEMPHYS Nufact2011@CERN-UNIGE

  21. T2KK vs. T2K II Comparison hep-ph/0504026 Total mass of the detectors = 0.54 Mton fid. mass 4 years neutrino beam + 4 years anti-neutrino beam 4MW! T2KK Mass hierarchy CP violation (sind≠0) T2K 3 s (thick) 2 s (thin) Nufact2011@CERN-UNIGE

  22. Precision CP requires … • T2K-T2KK comparison seems to indicate necessity of mass hierarchy resolution • importance of lifting sign Dm2 degeneracy • Comparison of different error treatments in nn-bar shows the relative cross section error affects CP sensitivity Supported by analysis in Kakuno-san’s talk n cross section measurement crucially important Nufact2011@CERN-UNIGE

  23. Does large q13 require new oscillation formula? Nufact2011@CERN-UNIGE

  24. Large q13 corrections to Cervera et al. formula Good perturbative formula for small q13 with s13 ~ Dm221 / Dm231 = e : 2nd order formula Cervera et al. 00 But, for large q13 ~10 deg. s13 ~\sqrt{e } higher order corrections needed PNC ~ s134, or ~ s132 e Computed: K. Asano-H.M. JHEPJune7, 2011 Nufact2011@CERN-UNIGE

  25. Some features of the new formula rD=Dm221/Dm231rA=a/Dm231D=Dm231 / 2E All the d dependence is in half-integer power of e General theorems! Nufact2011@CERN-UNIGE

  26. Correction terms are small All the correction terms are of order ~e2 General theorems! rD=Dm221/Dm231rA=a/Dm231D=Dm231 / 2E Nufact2011@CERN-UNIGE

  27. Is parameter degeneracy affected by large q13? Nufact2011@CERN-UNIGE

  28. P degeneracy well understood Cervera et al. formula HM-Uchinami JHEP10 Nufact2011@CERN-UNIGE

  29. Is P degeneracy unchanged for large q13? Cervera et al. formula • One can show on general ground that PNC must be order (Dm221 / Dm231)2 ~ 0.001 • Difference between Cervera sol. and our solutions is tiny (apart from a particular region) PNC ~ s134, or ~s132 Dm221 / Dm231 Nufact2011@CERN-UNIGE Asano-HM JHEP11

  30. What large q13 means? Nufact2011@CERN-UNIGE

  31. What large q13 means? • Large q13 is natural because in U=Vl+Vn two angles are large, and hence extremely small q13 is not expected, • Anarchy ? • The above argument assumes no symmetry is hidden symmetries which enforce q13 =0 somewhat discouraged (?) unless you have good reasons Nufact2011@CERN-UNIGE

  32. Large q13 in QLC context QLC based on observation: q12 + qC = p/4 Raidal 04, HM-A.Smirnov 04 Bimaximal mixing from neutrinos Bimaximal mixing from charged leptons Large q13 prefers bimaximal mixing from n Nufact2011@CERN-UNIGE

  33. Conclusion • large q13 opens up wide range of possibilities for hunting CP & mass hierarchy • While guerrilla type approach is possible, a charming case would be to determine all at once by a megaton-scale detector (+proton decay) Hyper-K • Yet, precision measurement would require resolution of sign-Dm2 degeneracy • Physical meaning of the large q13 has to be understood Nufact2011@CERN-UNIGE

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