NOW 2006 Neutrino Oscillation Workshop Conca Specchiulla 9

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

Me. V SOLAR NEUTRINOS Sun is a well-known source of low-energy O(Me. V) e, 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

HIGH ENERGY SOLAR NEUTRINOS § Solar flares (E~ 50 Me. V) § WIMP annihilation in the Sun (E~ Ge. V) Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

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 n( e) and (nm). (at production)

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 Te. V scale Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

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) Attenuation function

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 Ge. V, 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)]

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 3 n oscillation framework Kinematical massmixing term Alessandro Mirizzi NOW 2006 Dynamical MSW term (in matter) Conca Specchiulla, 14/09/2006

3 n FRAMEWORK U = U (q 12, q 13, q 23) Mixing parameters: Mass-gap parameters: M 2 = as for CKM matrix 2 2 - dm , + dm , ± Dm 2 2 2 “solar” n 3 +Dm 2 inverted hierarchy “atmospheric” dm 2 ≈ 7. 92 (1± 0. 09) 10 -5 e. V 2 sin 2 q 12 ≈ 0. 314 (1+0. 18 -0. 15) n 1 n 2 +dm 2/2 -dm 2/2 normal hierarchy n 1 n 2 n 3 +dm 2/2 -Dm 2 ≈ 2. 6 (1+0. 14 -0. 15) 10 -3 e. V 2 sin 2 q 23 ≈ 0. 45(1+0. 35 -0. 20) sin 2 q 13 = 0. 8+2. 3 -0. 8 10 -2 [Fogli et al. , hep-ph/0608060] In the following we will assume normal hierarchy Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

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

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

VACUUM APPROXIMATION (V=0) [C. Hettlage, K. Mannheim, J. Learned, astro-ph/9910208] (at the production) VACUUM OSCILLATIONS Many oscillation cycles in vacuum + n decoherence at Earth (energy resolution) (at Earth) [for q 23=p/4] Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

MATTER EFFECTS 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 Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

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 phaseaveraged vacuum case Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

OSCILLATED SAn FLUXES AT EARTH Uncertainty associated to 2 s range of q 23 Uncertainty associated to the initial fluxes OSCILLATIONS Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

SAn EVENT RATE Events rate in a km 3 detector (e. g. , Icecube) [A= 1 km 2] • 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 Ge. V • Huge cosmic ray bkg: only upgoing n useful ~ 4 useful m events/year above 100 Ge. V In ~10 years it would allow a “SA check” of q 23 Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006

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: • SAn are affected by peculiar matter effects (in principle, sensitive to q 13 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 Alessandro Mirizzi NOW 2006 Conca Specchiulla, 14/09/2006