SNO, SuperKamiokande data, antineutrinos and sterile neutrinos

Abstract

Allowing for antineutrinos ($\bar\nu_x$) and sterile neutrinos ($\nu_s$) to accompany LMA oscillations, we derive in a model independent way, upper bounds on their components in the solar flux, using the recent data from SNO and SuperKamiokande. Along with the general case (LMA + $\bar\nu_x$ + $\nu_s$) we consider the special cases where only $\bar\nu_x$ or $\nu_s$ are present. We obtain an upper bound on $\bar\nu_x$ which is independent of the $\nu_s$ component. In the no sterile case we obtain upper and lower bounds on $f_B$, the SSM normalization factor. We also investigate in the general case the common parameter range for $f_B$ and the $\bar\nu_x$, $\nu_s$ components and find that the upper bound on $\nu_s$ is hardly sensitive to the $\bar\nu_x$ component. In the absence of $\bar\nu_x$ we recover the $\nu_s$ upper bound existing in the literature. We finally present a simple $\chi^2$ analysis of all four cases considered.