A road map to solar neutrino fluxe, neutrino oscillation parameters, and tests for new physics

We analyze all available solar and related reactor neutrino experiments, as well as simulated future ^7Be, p-p, pep, and ^8B 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 (1 sigma) times the flux predicted by the BP00 standard solar model; the ^7Be neutrino flux is 0.97^{+0.28}_{-0.54} the predicted flux; and the ^8B flux is 1.01 + - 0.06 the predicted flux. The oscillation parameters are: Delta m^2 = 7.3^{+0.4}_{-0.6} 10^{-5} eV^2 and tan^2 theta_{12} = 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. A future ^7Be nu-e scattering experiment accurate to + -10% can reduce the uncertainty in the experimentally determined ^7Be 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^2 theta_{12} 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?