Piecing the Solar Neutrino Puzzle Together at SNO

Abstract

We perform an oscillation parameter-independent analysis of solar neutrino flux measurements from which we predict the charged-current rate at SNO relative to Standard Solar Model to be $R_{SNO}^{CC}=0.35_{-0.09}^{+0.16}(0.46_{-0.11}^{+0.13})$ for oscillations to active (sterile) neutrinos. By alternately considering the ${}^8$B flux normalization fixed and free, we find that the flux measured by Super-Kamiokande (SK) not being a result of oscillations is strongly disfavored for oscillations to active neutrinos. SNO will determine the best-fit value of the ${}^8$B flux normalization $\beta$ (equal to the neutral-current rate), without recourse to neutral-current measurements, from the derived relation $\beta =R_{SNO}^{NC}=5.85R_{SK}-4.85R_{SNO}^{CC}$. Using a simple parameterization of the fraction of high, intermediate, and low energy solar neutrinos starting above resonance, we reproduce the results of global analyses to good accuracy; we find that the LMA solution with a normal mass hierarchy is clearly favored. With $\beta$ free, our analysis for oscillations to active neutrinos gives $R_{SNO}^{NC}=\beta =1.34\pm 0.34$, which corresponds to $R_{SNO}^{CC}=0.28\pm 0.07$.

Comments: Version to appear in PLB