Proc. Neutrino Astrophysics - MPP Theory Group

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40 Solar Neutrinos: Where We Are and What Is Next? G. Fiorentini Dipartimento di Fisica dell’Universitá di Ferrara and Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, I-44100 Ferrara, Italy What has been Measured? All five experiments report a deficit of solar neutrinos with respect to the predictions of Standard Solar Models (SSMs), see Ref. [1]. What Have We Learnt on Solar Neutrinos, Independently of SSMs? Actually, the solar neutrino puzzle (SNP) is not just the discrepancy between experimental results and the predictions of standard solar models. Rather, experimental results look inconsistent among each other with the only assumption that the present total neutrino flux can be deduced from the present solar luminosity, unless something happens to neutrinos during the trip from Sun to Earth, see Fig. 1 and Refs. [1, 2, 3]. What Has Been Calculated? Accurate predictions of solar neutrino fluxes are anyhow extremely important. If neutrino masses (differences) are as small as suggested by several proposed solutions to the SNP, then the only way to measure neutrino masses is through the interpretation of future solar neutrino experiments, which requires accurate theoretical predictions of solar properties. Refined solar models are thus necessary. All these have to be confronted with the powerful helioseismic constraints, see Ref. [4], particularly for a quantitative (and conservative) determination of the accuracy of solar properties as deduced from helioseismology. Recent SSM calculations, using accurate equations of state, recent opacity calculations and including microscopic diffusion, look in agreement with heliosesimology, see Figs. 2 and 3 and Ref. [4]. Alternative solar models should be as successful as these are [5, 6]. Actually, one can exploit helioseismology within a different strategy. One can relax some assumptions on the most controversial ingredients of solar models (e.g. opacity and metal abundance) and determine them by requiring that helioseismic constraints are satisifed. These helioseismically constrained solar models (HCSM) all yield the same central temperature within about one percent [7]. The main uncertainties for the determination of solar neutrino fluxes arise now from nuclear physics measurements. After the succesful LUNA experiments at LNGS [8], the main uncertainties are now from the 3 He+ 4 He and 7 Be+p reactions. What Is Missing? In a prophetical paper of 1946 [9] Bruno Pontecorvo wrote: “direct proof of the existence of the neutrino ... must be based on experiments the interpretation of which does not require the law of conservation of energy, i.e. on experiments in which some characteristic process produced by free neutrinos ... is observed.”
Table 1: The proposed solutions, their fingerprints and the experiments looking at them. Proposed solutions Signatures Oscillation spectral Day-night Seasonal CC/NC at reactor deformation variation modulation events MSW small angle NO TINY TINY NO YES MSW large angle NO TINY YES NO YES JUST-SO NO YES NO YES YES Universal oscil. YES NO NO NO YES Experiment CHOOZ SUPERKAM. SUPERKAM. BOREXINO SNO Data now now now 2000 2000 The situation now looks very similar, just change existence with nonstandard properties, in that the strongest argument for a particle physics solution to the SNP arises from energy conservation (the luminosity constraint) and actually we need a direct footprint of some neutrino property, not predicted within the minimal standard model of electroweak interactions. The four most popular particle physics solutions (small and large angle MSW effect, just so oscillations and universal oscillations) all predict specific signatures which are being or will be tested by the new generation of experiments (Superkamiokande, Borexino, SNO, ...), see Table 1. The hypothesis of universal oscillation proposed in Ref. [10] has just been falsified by the recent negative result of CHOOZ [11]. This nice and small (in comparison with the gigantic solar neutrino devices) experiment at a nuclear reactor is cleaning some of the fog in the air. Let us wait and wish that (at least) one of the fingerprints of neutrino oscillations is detected by the new experiments. References [1] V. Castellani, S. Degl’Innocenti, G. Fiorentini, M. Lissia and B. Ricci, Phys. Rept. 281 (1997) 309. [2] S. Degl’Innocenti, G. Fiorentini and M. Lissia, Nucl. Phys. B (Proc. Suppl.) 43 (1995) 66. [3] J.N. Bahcall, Nucl. Phys. B (Proc. Suppl.) 38 (1995) 98. [4] S. Degl’Innnocenti, W.A. Dziembowski , G. Fiorentini and B. Ricci, Astrop. Phys. 7 (1997) 77. [5] S. Degl’Innocenti, G. Fiorentini and B. Ricci, astro-ph/9707133, Phys. Lett. B (1998) to appear. [6] S. Degl’Innocenti and B. Ricci, astro-ph/9710292, Astr. Phys. (1998) to appear. [7] B. Ricci, V. Berezinsky, S. Degl’Innocenti, W.A. Dziembowski and G. Fiorentini, Phys. Lett. B 407 (1997) 155. [8] LUNA collaboration, Phys. Lett. B 389 (1996) 452. See also M.Junker, these proceedings. 41
Page 1 and 2: arXiv:astro-ph/9801320v1 30 Jan 199
Page 3: Preface This was the fourth worksho
Page 6 and 7: vi S.J. Hardy Quasilinear Diffusion
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Page 11 and 12: History of Neutrino Physics: Pauli
Page 13 and 14: Brief an Oskar Klein, Stockholm, vo
Page 15 and 16: Recent observations with the Hubble
Page 17 and 18: MACHO sample of ∼100,000 light cu
Page 19: Solar Neutrinos
Page 22 and 23: 14 In the depth range where an abun
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Page 26 and 27: 18 [3] J.N. Bahcall and H.A. Bethe,
Page 28 and 29: 20 the opacity has a very slowly ch
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Page 32 and 33: 24 known true source activity. The
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Page 36 and 37: 28 Events/day/kton/bin 0.3 0.25 0.2
Page 38 and 39: 30 log(Δm 2 (eV 2 log(Δm )) 2 (eV
Page 40 and 41: 32 Table 1: Neutrino event rates in
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Page 44 and 45: 36 Measurements of Low Energy Nucle
Page 46 and 47: 38 Figure 1: The S(E) factor of 3 H
Page 50 and 51: 42 [9] B. Pontecorvo, Chalk River R
Page 52 and 53: 44 Figure 2: The difference between
Page 55 and 56: Phenomenology of Supernova Explosio
Page 57 and 58: Figure 2: Theoretical classificatio
Page 59 and 60: Supernova Rates Bruno Leibundgut Eu
Page 61 and 62: galaxies, however, and the statisti
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Gamma-Ray Burst Observations D.H. H
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Figure 1: The cumulative distributi
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[7] Lilly, S., in Critical Dialogue
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) Phase Transitions in Neutron Star
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after the collapse began (nb., no e
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Models of Coalescing Neutron Stars
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Figure 2: Contour plots of the mass
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From our torus models we find that
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High-Energy Neutrinos
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110 in gamma-rays. However, the acc
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112 Atmospheric Muons and Neutrinos
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114 Today, however, charm productio
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116 Atmospheric Neutrinos in Super-
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118 number of events 300 200 100 (a
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120 Acknowledgements D.K. is suppor
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122 Key signatures for νµ nucleon
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124 (a.u) 0.5 0.4 0.3 0.2 0.1 0 0 1
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126 However, in order to operate th
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128 could be gravitationally captur
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130 Ground-Based Observation of Gam
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132 Figure 2: Sensitivities in unit
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134 Crab flux Figure 4: Gamma-ray f
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136
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Helium Absorption and Cosmic Reioni
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Non-Standard Big Bang Nucleosynthes
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) Non-standard Neutrino Properties
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some heating of the plasma. In cont
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Big Bang Nucleosynthesis With Small
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Neutrinos and Structure Formation i
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Photon and Neutrino Backgrounds The
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The (photon) temperature at aeq is
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spectrum has therefore changed to 1
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Figure 4: Growth of structure in CD
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Future Prospects
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162 Figure 1: Calorimetric β − s
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164 References [1] F. Gatti: Procee
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166 The frequency of Galactic super
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168 Table 1: Comparison of proposed
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170 Neutrinos in Astrophysics José
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172 N eq 7 6.5 6 5.5 5 4.5 4 3.5 3
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174 Figure 4: SN 1987A bounds on FC
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176 [5] A. Joshipura and J. W. F. V
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178 Some Neutrino Events of the 21s
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180 2099: Relic Neutrinos And last
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182
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184 Tuesday, Oct. 21: Supernova Neu
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186 Michael Altmann Technische Univ
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188 Paolo Gondolo Max-Planck-Instit
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190 Patrizia Meunier Max-Planck-Ins
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192 Torsten Soldner Technische Univ
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194 A Experimental Particle Physics
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196 C Astrophysics and Cosmology C1
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