Neutrino and Cosmic Ray Oscillations: Current State and Future Prospects

1. Conveners: Laura Patrizii(INFN, Bologna) Eligio Lisi (INFN, Bari) IFAE’06, Pavia, 19-21 Aprile 2006 Sommario della Sessione: Neutrini e Raggi Cosmici Speakers: Maximiliano Sioli (U. di Bologna) Aldo Ianni (INFN, LNGS) Marco Cirelli (Yale Univ.) Flavio Gatti (INFN, Genova) Maura Pavan (U. di Milano Bicocca) Michele Frigerio (CEA/Saclay) Alessandro Mirizzi (Univ. di Bari) Davide Meloni (INFN, Roma I) Michele Maltoni (ICTP, Trieste) Giorgio Riccobene (INFN, LNS) Daniel De Marco (U. of Delaware) Andrea Chiavassa (Univ. di Torino) Vincenzo Vitale (Univ. di Udine) Paola Salvini (INFN, Pavia)

2. Super-K KamLAND Neutrino masses, mixing and oscillations are established facts m2-driven oscillations m2-driven oscillations (about half-period seen in both cases) Frequencies and amplitudes can be embedded in a 3 framework

3. Abs.scale Normal hierarchy… OR… Inverted hierarchy mass2 splittings 3 +m2 2 m2 m2 1 -m2 3 Current interpretation of world data (-LSND) stable around the following scenario (with flavorse):

4. A more quantitative summary of world neutrino oscillation data as of 2005 (with 2 errors) 2006, after MINOS (prelim.) Good news for CNGS-OPERA, since tau event rate ~(m2)2: (2.6/2.4)2=1.17

5. Max Sioli (“Oscillazioni di neutrini con sorgenti artificiali”): MINOS 2006 OPERA ~2006+5 (After MINOS: 12.8 x 1.17 = 15.0)

6. (2 ,3)oscillation parameters: Significantly higher accuracy in next-generation long-baseline experiments T2K, NOvA (Max Sioli)

7. (1 ,2)oscillation parameters: Currently dominated by SNO (mixing) and by KamLAND (mass2 difference). Some improvements expected in both expt.

8. Solar matter effects (MSW) with standard size (V = 2 GF Ne ) basically confirmed, but factor ~2 deviations still allowed (from V(x)  aMSWV(x) with aMSW free)

9. Therefore, important to pursue spectroscopy in the poorly known low-energy solar  range (Aldo Ianni, “Oscillazioni di neutrini con sorgenti naturali”) BOREXINO @ LNGS mission: Measure Be flux

10. …and maybe also (A. Ianni): pep neutrinos with Borexino • Basic idea : reduce 11C cosmogenic background • Method : tagging 11C by tackling the produced (95%) neutrons in spallation interactions Strong competitors: KamLAND (Be, pep) SNO+ (pep) Important to start the experiment as soon as possible …

11. The elusive mixing angle 13: current status (Consistency of all data for small 13 is nontrivial)

12. The elusive mixing angle 13: future prospects (Max Sioli) 13fundamental to access mass hierarchy and leptonic CP violation

13. Abs.scale Normal hierarchy… OR… Inverted hierarchy mass2 splittings Q driven by matter effects (only in matter & for s13>0) Q driven by m2 (in any case, but very hard!) 3 +m2 2 m2 m2 1 -m2 3 Hierarchy = sign(m2). In order to test the sign, we need interference of oscillation phase (m2 L/E) with another “phase” Q having known sign. Two options (barring exotics): Basically all current projects focus on the first option

14. If nature is kind enough, this option might be exploited in the next galactic supernova explosion (~3/century) (Alessandro Mirizzi, “Fisica dei neutrini da Supernova”) E.g., observation of non-monotonic time spectra through inverse beta decay in water-Ch. detectors would: Establish inverse hierarchy Monitor the SN shock wave Establish a lower bound on sin213 (with sensitivity down to 10-4)

15. 13fundamental to access also leptonic CP violation (which vanishes when the full 3 parameter space is reduced to an effective 2 one). If13nonzero, however, attempts to determine13andCP in future long-baseline experiments must face the occurrence of multiple solutions (“degeneracies” or “clones”), as discussed by Davide Meloni and Michele Maltoni Several ways out have been explored through prospective simulations

16. 2- golden+silver channels solo golden E.g., by combining different appearance channels at a future neutrino factory: (Davide Meloni, “Violazione di CP nel settore leptonico”)

17. Or, by combining future long-baseline accelerator and atmospheric neutrino data: (Michele Maltoni, “Sinergie fra neutrini da acceleratore e atmosferici”)

18.  decay: m2i  0 can affect spectrum endpoint. Sensitive to the “effective electron neutrino mass” (Flavio Gatti): 2)02 decay: Can occur if m2i  0 and =. Sensitive to the “effective Majorana mass” and phases (Maura Pavan): 3) Cosmology: m2i  0 can affect large scale structures in (standard) cosmology constrained by CMB+other data (Marco Cirelli). Probes: Absolute neutrino mass observables: (m, m, )

19. 2 eV 0.2 eV 20 eV 1990 1995 2000 2005 2010 2015 MAINZ 2.2 eV 20-10 eV KATRIN TROITZK 2.2 eV spettrometri magnetici spettrometri elettrostatici Spettrometri Calorimetri 26 eV95%CL MANU MARE Sandro Vitale 1985 187Re 15 eV90%CL MIBETA 20 eV 2 eV 0.2 eV 1995 2005 1990 2000 2010 2015 Italian contribution to calorimetric spectroscopy and m limits, in perspective (Flavio Gatti)

20. 0n2b 2530 keV 130 Te: Cuoricino NOW Cuoricino within 3 years Italian contributions to m searches: Pioneering +… Cuoricino, Cuore, Gerda … (Maura Pavan) started in April 2003 long interruption for maintenance t1/20n > 2 10 24 y at 90% C.L. <mn> < 0.3-0.7 eV <mn> < 0.2-0.5 eV

21. Constraints on  from CMB + Large Scale Structure data (Marco Cirelli)

22. m oscill. allowed  Oscillations fix the mass splittings and thus induce positive correlations between any pair of the three observables (m, m, ), e.g.: i.e., if one observable increases, the other one (typically) also increases

23. Oscillation data only: Positive correlations Partial overlap between NH and IH Large (intrinsic) m spread due to unknown Majorana phases

24.  decay: no signal so far. Mainz & Troitsk expts: m < O(eV) 02 decay, no signal in all experiments, except in the most sensitive one to date (Heidelberg-Moscow). Rather debated claim. Claim accepted: m in sub-eV range (with large uncertainties) Claim rejected: m < O(eV). Cosmology. Upper bounds:  < eV/sub-eV range, depending on several inputs and priors. E.g., Lyman- data crucial to reach sub-eV bounds (but: systematics?) Current info from non-oscillation experiments:

25. 02 claim rejected: cosmological bound dominates [Green dotted line: a more aggressive <0.3 eV bound]

26. 02 claim accepted: tension with cosmological bound(s) } expt+theo error (Green dotted line: <0.3 eV ) No reasonable combination at face value, but: too early to draw definite conclusions

27. Absolute masses, hierarchy, CP violation, Majorana/Dirac nature, more accurate oscillation parameters also crucial to constrain model building (Michele Frigerio, “Modelli teorici per le masse dei neutrini”) … together with the possible connections with other sectors of physics …

28. … including Higgs physics (Michele Frigerio) … or cosmology, with radically new ideas (Marco Cirelli) In both cases, we need to understand fundamental scalar fields and their couplings, and we all hope to open this window with the LHC!

29. Dreaming about future, precise nonoscillation + oscillation data … Check overall consistency … Identify the hierarchy … Probe the Majorana phases … (and the CP phase too…)

30. Cosmic Rays -> Laura Patrizii