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.

Comments: 13 pages, 4 eps figures, final version to appear in JHEP