Robust signatures of solar neutrino oscillation solutions

Abstract

With the goal of identifying signatures that select specific neutrino oscillation parameters, we test the robustness of global oscillation solutions that fit all the available solar and reactor experimental data. We use three global analysis strategies previously applied by different authors and also determine the sensitivity of the oscillation solutions to the critical nuclear fusion cross section, S 17 (0), for the production of 8 B. Our standard results make use of the precise new measurement of S 17 (0) by Junghans et al. The globally favored solutions are, in order of goodness of fit: LMA(the only solution at 2σ), LOW, and VAC. The NC to CC ratio for SNO is predicted by the standard global analysis to be 3.45 +0.70 −0.54 (1σ) which is separated from the no-oscillation value of 1.0 by much more than the expected experimental error. The predicted range of the day-night difference in CC rates is 8.3 +5.0 −5.6 (1σ)%. A measurement by SNO of either a NC to CC ratio > 3.3 or a day-night difference > 10%, would favor a small region of the currently allowed LMA neutrino parameter space. The global oscillation solution predicts a 7 Be neutrino-electron scattering rate in BOREXINO and KamLAND in the range 0.65 +0.04 −0.03 (1σ) of the BP00 standard solar model rate, a prediction which can be used to test both the solar model and the neutrino oscillation theory. Only the LOW solution predicts a large day-night effect(≤ 42%, 3σ) in BOREXINO and KamLAND. For the reactor KamLAND experiment, the LMA solution predicts a charged current rate relative to the standard model of 0.44 +0.22 −0.07 (1σ), E threshold = 1.22 MeV. We have also evaluated the effects of including preliminary Super-Kamiokande data for 1496 days of observations.

Before and After: How has the SNO NC measurement changed things?

“…In that case, the predicted rates for the LMA solution are increased by about 1% and the predicted values for the LOW and vacuum solutions are decreased by between 2% and 7%. The rates shown in table 6 are also very similar to the rates that were expected [4] prior to the recent SNO measurements.…”

“…ref. [4]). Following the SNO NC measurement, we prefer to use the neutrino data to determine the flux normalization and therefore to test, rather than assume, the standard solar model prediction for the 8 B neutrino flux.…”

“…The global solutions obtained here are calculated using the methods described in our recent paper [4] (see especially section 3.3 of ref. [4]) but also include some refinements in addition to the new SNO data.…”

Solar neutrinos: Global analysis with day and night spectra from SNO

“…Notice that in the SNO analysis [4] the LOW solution exists marginally at 3σ level. Inclusion of the SK data which contain information about zenith angle distribution (zenith spectra) worsen the fit (this effect has also been observed in [13]). …”

A flavor symmetry model for bilarge leptonic mixing and the lepton masses

“…4 However, in the light of recent atmospheric [5][6][7][8][9] and solar [10][11][12][13][14][15][16][17] neutrino experimental results, it seems to be difficult to extend this idea to the neutrinos. Especially, the result that, among the different possible solutions of the solar neutrino problem, the Mikheyev-Smirnov-Wolfenstein (MSW) [18][19][20] large mixing angle (LMA) solution is the presently preferred one [21][22][23] 5 , draws a picture of the involved flavor symmetries and their breaking mechanisms that differs remarkably from the early approaches, which have been applied to the quark sector. In the "standard" parameterization, the MSW LMA solution implies that we have a bilarge mixing scenario in the lepton sector in which the solar mixing angle θ 12 is large, but not necessarily close to maximal, the atmospheric mixing angle θ 23 is nearly maximal, and the reactor mixing angle θ 13 is small.…”