Global analyses as a road map to solar neutrino fluxes and oscillation parameters

We analyze all available solar and related reactor neutrino experiments, as well as simulated future Be, p − p, pep, and B solar neutrino experiments. We treat all solar neutrino fluxes as free parameters subject to the condition that the total luminosity represented by the neutrinos equals the observed solar luminosity (the ‘luminosity constraint’). Existing experiments show that the p−p solar neutrino flux is 1.01 ± 0.02 (1σ) times the flux predicted by the BP00 standard solar model; the Be neutrino flux is 0.97 −0.54 the predicted flux; and the B flux is 1.01 ± 0.06 the predicted flux. The oscillation parameters are: ∆m = 7.3 −0.6 × 10−5 eV and tan θ12 = 0.42 +0.08 −0.06. We evaluate how accurate future experiments must be to determine more precisely neutrino oscillation parameters and solar neutrino fluxes, and to elucidate the transition from vacuum-dominated to matter-dominated oscillations at β = 2 √ 2GFneEν/∆m 2 ∼ cos 2θ12. A future Be ν−e scattering experiment accurate to ±10% can reduce the uncertainty in the experimentally determined Be neutrino flux by a factor of four and the uncertainty in the p− p neutrino flux by a factor of 2.5 (to ±0.8%). A future p − p experiment must be accurate to better than ±3% to shrink the uncertainty in tan θ12 by more than 15%. Based upon quantitative analyses of present and simulated future experiments, we answer the question: Why perform low-energy solar neutrino experiments?