
While standard solar model (SSM) predictions depend on approximately 20 input parameters, SSM neutrino flux predictions are strongly correlated with a single model output parameter, the core temperature Tc. Consequently, one can extract physics from solar neutrino flux measurements while minimizing the consequences of SSM uncertainties, by studying flux ratios with appropriate powerlaw weightings tuned to cancel this Tc dependence. We reexamine an idea for constraining the primordial C + N content of the solar core from a ratio of CNcycle O15 to ppchain B8 neutrino fluxes, showing that nonnuclear SSM uncertainties in the ratio are small and effectively governed by a single parameter, the diffusion coefficient. We point out that measurements of both CNI cycle neutrino branchesO15 and N13 betadecaycould, in principle, lead to separate determinations of the core C and N abundances, due to outofequilibrium CNcycle burning in the cooler outer layers of the solar core. Finally, we show that the strategy of constructing ¿minimum uncertainty¿ neutrino flux ratios can also test other properties of the SSM. In particular, we demonstrate that a weighted ratio of Be7 and B8 fluxes constrains a product of Sfactors to the same precision currently possible with laboratory data.
