Solar neutrinos: global analysis and implications for SNO

We present a global analysis of all the available solar neutrino data treating consistently the 8B and hep neutrino fluxes as free parameters. The analysis reveals at 99.7% C.L. eight currently-allowed discrete regions in two-neutrino oscillation space, five regions corresponding to active neutrinos and three corresponding to sterile neutrinos. Most of the allowed solutions are robust with respect to changes in the analysis procedure, but the traditional vacuum solution is fragile. The globally-permitted range of the 8B neutrino flux, 0.45 to 1.95 in units of the BP2000 flux, is comparable to the 3 sigma range allowed by the standard solar model. We discuss the implications for SNO of a low mass, Delta m^2 ~ 6 times 10^{-12} eV^2, vacuum oscillation solution, previously found by Raghavan, and by Krastev and Petcov, but absent in recent analyses that included Super-Kamiokande data. For the SNO experiment, we present refined predictions for the charged-current rate and the ratio of the neutral-current rate to charged-current rate. The predicted charged-current rate can be clearly distinguished from the no-oscillation rate only for the LMA solution. The predicted ratio of the neutral-current rate to charged-current rate is distinguishable from the no-oscillation ratio for the LMA, SMA, LOW, and VAC solutions for active neutrinos.Comment: viewgraphs and related material at http://www.sns.ias.ed

Cubic Mass Relation in SU(3)×U(1)\rm SU(3)\times U(1) Electroweak Theory

In the 331 model, lepton number may be explicitly broken by trilinear scalar self couplings. This leads to neutrino masses proportional to the cube of the corresponding charged lepton mass, with consequences for solar neutrinos and for hot dark matter.Comment: 12 pages (3 figures appended to RevTeX file), IFP-465-UN

What will the first year of SNO show?

The ratio of the measured to the predicted standard model CC event rates in SNO will be 0.47 if no oscillations occur. The best-fit active oscillation predictions for the CC ratio are: 0.35-39 (MSW) and 0.38-42 (vacuum) (all for a 5 MeV energy threshold), typically about 20% less than the no-oscillation expectation. We calculate the predicted ratios for six active and sterile neutrino oscillation solutions allowed at 99% CL and determine the dependence of the ratios on energy threshold. If the high-energy anomaly observed by SuperKamiokande is due to an enhanced hep flux, MSW active solutions predict that out of a total of 5000 CC events above 5 MeV in SNO between 49 and 54 events will be observed above 13 MeV whereas only 19 events are expected for no-oscillations and a nominal standard hep flux.Comment: Phys Lett accepted. Editorial corrections. Related material and viewgraphs at http://www.sns.ias.edu/~jn

Do hep neutrinos affect the solar neutrino energy spectrum?

If the low energy cross section for 3He + p goes to 4He + e + nu_e, the `hep' reaction, is > 20 times larger than the best (but uncertain) theoretical estimates, then this reaction could significantly influence the electron energy spectrum produced by solar neutrino interactions and measured in the SuperKamiokande, SNO, and ICARUS experiments. We compare predicted energy spectra for different assumed hep fluxes and different neutrino oscillation scenarios with the observed SuperKamiokande spectrum. The spectra with enhanced hep contributions provide better fits to the SuperKamiokande data.Comment: Accepted Phyics Letters B. Related information at http://www.sns.ias.edu/~jnb . LaTeX file. 12 pages including 2 figures. Typo in Table 2 correcte

Correlations of Solar Neutrino Observables for SNO

Neutrino oscillation scenarios predict correlations, and zones of avoidance, among measurable quantities such as spectral energy distortions, total fluxes, time dependences, and flavor content. The comparison of observed and predicted correlations will enhance the diagnostic power of solar neutrino experiments. A general test of all presently-allowed (two neutrino) oscillation solutions is that future measurements must yield values outside the predicted zones of avoidance. To illustrate the discriminatory power of the simultaneous analysis of multiple observables, we map currently allowed regions of neutrino masses and mixing angles onto planes of quantities measurable with the Sudbury Neutrino Observatory (SNO). We calculate the correlations that are predicted by vacuum and MSW (active and sterile) neutrino oscillation solutions that are globally consistent with all available neutrino data. We derive approximate analytic expressions for the dependence of individual observables and specific correlations upon neutrino oscillations parameters. We also discuss the prospects for identifying the correct oscillation solution using multiple SNO observables.Comment: Accepted Phys Rev D. Included new figure. Related material http://www.sns.ias.edu/~jn

Editor: W. Haxton

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