1. Neutrinos and Z-bursts Dmitry Semikoz UCLA (Los Angeles) & INR (Moscow)

2. Neutrino Oscillation Workshop, September 11-17, 2004 Overview Introduction: Z-burst model: general idea Problem of gamma-ray flux Production of UHECR neutrinos Neutrino mass and Z-burst Experimental limits on neutrino flux Conclusions

3. Neutrino Oscillation Workshop, September 11-17, 2004 The Greisen-Zatsepin-Kuzmin (GZK) effect Nucleons can produce pions on the cosmic microwave background nucleon   -resonance multi-pion production pair production energy loss pion production energy loss pion production rate  sources must be in cosmological backyard within 50-100 Mpc from Earth (compare to the Universe size ~ 5000 Mpc)

4. Neutrino Oscillation Workshop, September 11-17, 2004 AGASA and HiRes experiments HiRes: astro-ph/0208301 AGASA: astro-ph/0209422

5. Neutrino Oscillation Workshop, September 11-17, 2004 Z-burst mechanism Resonance energy E = 4.2 10 21 (1 eV/m ) eV Cross section Works for UHECR only if m   eV T.Weiler, 1982 D.Fargion, B.Mele and A.Salis 1997; T.Weiler, 1997

6. Neutrino Oscillation Workshop, September 11-17, 2004 Cross sections for neutrino interactions with relict background and 

7. Neutrino Oscillation Workshop, September 11-17, 2004 Z-burst mechanism Average cross section Relic neutrino density Mean free path of neutrino is L = 150 Gpc >> L univ T.Weiler, 1982 D.Fargion, B.Mele and A.Salis 1997; T.Weiler, 1997

8. Neutrino Oscillation Workshop, September 11-17, 2004 Problem of secondary gamma-ray flux

9. Neutrino Oscillation Workshop, September 11-17, 2004 The high energy gamma ray detector on the Compton Gamma Ray Observatory (20 MeV - ~20 GeV) EGRET: diffuse gamma-ray flux

10. Neutrino Oscillation Workshop, September 11-17, 2004 Problem: too high diffuse  - ray flux m  1 eV (Yoshida,Sigl,Lee,1998)

11. Neutrino Oscillation Workshop, September 11-17, 2004 Possible solution: local overdensity but at least factor 20 over 5 Mpc is needed Here factor 100 over 20 Mpc

12. Neutrino Oscillation Workshop, September 11-17, 2004 Neutrino overdensity in galaxy clusters S.Singh, C-P.Ma, Phys.Rev.D 67, 023506 (2003)

13. Neutrino Oscillation Workshop, September 11-17, 2004 Non-uniform distribution of sources Kalashev, Kuzmin, D.S. and Sigl, hep-ph/0112351

14. Neutrino Oscillation Workshop, September 11-17, 2004 Production of UHE neutrinos

15. Neutrino Oscillation Workshop, September 11-17, 2004 Neutrinos from pion production in sources p n Conclusion: photon and neutrino fluxes from pion production are connected in well-defined way. If we know one of them we can predict other one.

16. Neutrino Oscillation Workshop, September 11-17, 2004 Sources of both  and O.Kalashev, V.Kuzmin, D.S. and G.Sigl, hep-ph/0112351

17. Neutrino Oscillation Workshop, September 11-17, 2004 X -> only (Gelmini-Kusenko, 2001) Secondary gamma-ray flux in production just 10% of neutrino flux V.Berezinsky, M.Kachelriess and S.Ostapchenko, hep-ph/0205218

18. Neutrino Oscillation Workshop, September 11-17, 2004 Neutrino mass?

19. Neutrino Oscillation Workshop, September 11-17, 2004 Can we define neutrino mass? Yes ( Z.Fodor, S.Katz andA.Ringwald, hep-ph/0105164 )

20. Neutrino Oscillation Workshop, September 11-17, 2004 Dependence from m   equally good fit at any mass. m =0.1 eV m =1 eV Many free parameters: source distribution, magnetic field, radio background

21. Neutrino Oscillation Workshop, September 11-17, 2004 Dependence on radio background   equally good fit at any mass. Z.Fodor, S.Katz and A.Ringwald, hep-ph/0203198

22. Neutrino Oscillation Workshop, September 11-17, 2004 Experimental constraints on UHE neutrinos

23. Neutrino Oscillation Workshop, September 11-17, 2004 e + n  p + e - e - ... cascade  relativist. pancake ~ 1cm thick,  ~10cm  each particle emits Cherenkov radiation  C signal is resultant of overlapping Cherenkov cones  for >> 10 cm (radio) coherence  C-signal ~ E 2 nsec negative charge is sweeped into developing shower, which acquires a negative net charge Q net ~ 0.25 E cascade (GeV). Threshold > 10 16 eV Experiments: GLUE, RICE, FORTE

24. Neutrino Oscillation Workshop, September 11-17, 2004 Goldstone Lunar UHE Neutrino Search (GLUE) P. Gorham et al., PRL 93, 041101 (2004) Two antennas at JPL’s Goldstone, Calif. Tracking Station l limits on >10 20 eV ’s l regolith atten. len. ~20 m l ~123 hours livetime l [V  ] eff ~600 km 3 -sr l datataking complete Earlier experiment: 12 hrs using single Parkes 64m dish in Australia: T. Hankins et al., MNRAS 283, 1027 (1996)

25. Neutrino Oscillation Workshop, September 11-17, 2004 FORTE satellite (Fast On-orbit Recording of Transient Events) Main mission: synaptic lightning observation Viewed Greenland ice with appropriate trigger (1997-99)  1.9 MILLION km 3  38 days £ 6% Can self-trigger on transient events in 22MHz band in VHF band (from 30 to 300 MHz) Event characterization  polarization  ionospheric group delay and birefringence  timing Log-periodic antennas N. Lehtinen et al., PRD 69, 013008 (2004)

26. Neutrino Oscillation Workshop, September 11-17, 2004 FORTE

27. Neutrino Oscillation Workshop, September 11-17, 2004 GLUE, FORTE and WMAP strongly disfavor Z-burst model D.S. and G.Sigl, hep-ph/0309328

28. Neutrino Oscillation Workshop, September 11-17, 2004 ANITA An tarctic I mpulsive T ransient A rray Flight in 2006

29. Neutrino Oscillation Workshop, September 11-17, 2004 ANITA will rule out (confirm???) Z-burst model ANITA -------------

30. Neutrino Oscillation Workshop, September 11-17, 2004 CONCLUSIONS Z-burst model can explain UHECR above GZK cutoff, but produce large gamma-ray flux. One can not define neutrino mass from this model: too many unknown parameters. This model is strongly disfavored by limits on neutrino flux from GLUE and FORTE experiments combined with cosmological bound on neutrino mass. Finally this model will be tested in 2006-2007 by ANITA experiment.