Implications for dark matter particles of searches for energetic solar neutrinos

Abstract

We investigate whether recent searches for energetic solar neutrinos give new constraints on candidate dark-matter particles such as photinos γ and higgsinos h̃, in view of the astrophysical and particle physics uncertainties. Previous quark model estimates of the elastic cross sections responsible for γ or h̃ capture in the sun can be improved using hyperon decay data, but are thrown into doubt by recent European Muon Collaboration data on the spin-dependent proton structure function, which reduce the estimate of σ( γ p ) by a factor up to four. We emphasize the need to include charm and bottom quark fragmentation effects when calculating the flux of neutrinos from dark matter annihilation events, which may reduce the observable flux by a factor ∼ 2. Even the most stringent upper limits from the Fréjus experiment still allow a local γ or h̃ density considerably above the range of 0.20–0.43 GeV/cm 3 favoured by astrophysics, and no range of m γ or m h ̃ can yet be excluded.