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Alessandro MIRIZZI (Dip. di Fisica & INFN, BARI, Italy)

NOW 2006 – Neutrino Oscillation Workshop Conca Specchiulla, 9-16 September 2006. SOLAR ATMOSPHERE NEUTRINOS. Alessandro MIRIZZI (Dip. di Fisica & INFN, BARI, Italy). Based on: G.L. Fogli, E. Lisi, A.M ., D. Montanino, P.D. Serpico, hep-ph/0608321. OUTILNE.

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Alessandro MIRIZZI (Dip. di Fisica & INFN, BARI, Italy)

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  1. NOW 2006 – Neutrino Oscillation Workshop Conca Specchiulla, 9-16 September 2006 SOLAR ATMOSPHERE NEUTRINOS Alessandro MIRIZZI (Dip. di Fisica & INFN, BARI, Italy) Based on: G.L. Fogli, E. Lisi, A.M., D. Montanino, P.D. Serpico, hep-ph/0608321

  2. OUTILNE • Sun as high energy neutrino source • Solar atmosphere neutrino (SAn) fluxes • SAn oscillations in Sun and in vacuum • Event rate in HE neutrino telescopes • Conclusions Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  3. MeV SOLAR NEUTRINOS Sun is a well-known source of low-energy O(MeV) ne, produced in its core by nuclear reactions Solar neutrinos provide us with solid evidence for  mass & mixing, and with a beautiful synthesis of physics and astrophysics. Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  4. HIGH ENERGY SOLAR NEUTRINOS • Solar flares (E~ 50 MeV) • WIMP annihilation in the Sun (E~ GeV) Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  5. SOLAR ATMOSPHERE NEUTRINOS (SAn) Cosmic rays hitting the solar atmosphere lead to the production of secondary particles via high-energy pp interaction, the decay of which produces a flux of ne and nm. ( ) ( ) (at production)

  6. . SAn ORIGINAL FLUXES [G.Ingelman & M.Thunman, hep-ph/9604288] SAn flux calculated basing on Montecarlo models (PHYTIA & JETSET) for high energy particle interactions at different impact parameter 0<b<R. b The original fluxes are almost b-independent below the TeV scale Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  7. Attenuation function SAn ATTENUATION IN THE SUN • While propagating in Sun, SAn are affected by • oscillations in matter • attenuations through weak interactions with nucleons of the solar medium. Interaction cross sections approximatively the same: oscillations and absorptions can be factorized [V.Naumov, hep-ph/0112249] Absorptions taken into account multiplying the original n fluxes by an overall attenuation function A(E,b)

  8. UNOSCILLATED SAn FLUXES The factorization of oscillations and absorptions allows to take as unoscillated input the attenuated fluxes, integrated over the solar disk. For E<100 GeV, no simulation We assume as in [C.Hettlage, K.Mannheim, J. Learned, astro-ph/9910208] with 1.75<g<2.45 to take into account uncertainties related to heliomagnetic effects [D.Seckel, T.Stanev, T.K. Gaisser, Astrophys. J. 382, 652 (1991)]

  9. SAn OSCILLATIONS SAn fluxes are affected by oscillation effects in Sun and then in vacuum. We have solved numerically MSW neutrino equations considering the standard 3n oscillation framework Dynamical MSW term (in matter) Kinematical mass-mixing term Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  10. M2 = - , + , ± Dm2 “solar” “atmospheric” dm2 dm2 2 2 3n FRAMEWORK Mixing parameters:U = U (q12, q13, q23) as for CKM matrix Mass-gap parameters: dm2≈ 7.92 (1±0.09)  10-5 eV2 sin2q12 ≈ 0.314 (1+0.18-0.15) Dm2 ≈ 2.6 (1+0.14-0.15)  10-3 eV2 sin2q23 ≈ 0.45(1+0.35-0.20) sin2q13 = 0.8+2.3-0.8  10-2 n3 • Dm2 inverted hierarchy n1 • dm2/2 n1 • dm2/2 n2 n2 -dm2/2 -dm2/2 n3 -Dm2 normal hierarchy [Fogli et al., hep-ph/0608060] In the following we will assume normal hierarchy Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  11. + ( n ) ; - ( n ) NEUTRINO POTENTIAL Matter effects on n oscillations crucially depend on neutrino potential in Sun: Potentially large matter effects are expected at resonance when or In normal hierarchy the resonance condition can be fulfilled only by n

  12. OSCILLATED n FLUXES SAn fluxes at Earth expressed in terms of the oscillation probabilities • appearence ! …. But, challenging to be detected at E~ 102 GeV Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  13. VACUUM OSCILLATIONS (at Earth) [for q23=p/4] VACUUM APPROXIMATION (V=0) [C.Hettlage, K.Mannheim, J. Learned, astro-ph/9910208] (at the production) Many oscillation cycles in vacuum + n decoherence at Earth (energy resolution) Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  14. Matter effects High energy vacuum limit (l»R) Resonance condition never realized in n channel. Matter effects negligible. Matter effects suppressed after averaging over n+n MATTER EFFECTS Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  15. AVERAGING OVER THE IMPACT PARAMETER Given the limited angular resolution of the detector (dq>1°), one has to integrate over the solar disk (qsun~0.26°). Matter effects strongly suppressed after the averaging. Oscillation probabilities very similar to the phase-averaged vacuum case Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  16. Uncertainty associated to 2s range of q23 Uncertainty associated to the initial fluxes OSCILLATED SAn FLUXES AT EARTH OSCILLATIONS Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  17. SAn EVENT RATE Events rate in a km3 detector (e.g., Icecube) [A= 1 km2] • SAn signal dominates over the atmospheric bkg in the solar angular bin. • Mismatch between the produced m and the original n: in the observable angular bin S/N ~ 1 for E > 100 GeV • Huge cosmic ray bkg: only upgoing n useful ~ 4 useful m events/year above 100 GeV In ~10 years it would allow a “SAn check” of q23 Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

  18. SAn are affected by peculiar matter effects (in principle, sensitive to q13 and to mass hierarchy). However, (i) the averaging over the impact parameter; (ii) the indistinguishability between n and n strongly contribute to suppress them. • “Vacuum” approximation is accurate enough to characterize SAn oscillation effects. The detection of SAn in large telescope detectors would: • test n vacuum oscillation at high energy scale • provide information on solar astrophysics • perhaps provide signature of new neutrino physics and eventually of dark matter CONCLUSIONS The Sun is a valuable source of high-energy neutrinos, produced by cosmic ray interactions in solar atmosphere (“solar atmosphere neutrinos”, SAn) We have performed a detailed study of SAn oscillations, including matter effects in the Sun: Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

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