Search for a stable six-quark state at BABAR

Abstract

Recent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the first search for a stable, doubly strange six-quark state in ϒ → SΛ¯ Λ¯ decays based on a sample of 90 × 106ϒð2SÞ and 110 × 106ϒð3SÞ decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined ϒð2S; 3SÞ → SΛ¯ Λ¯ branching fraction in the range ð1.2–1.4Þ × 10−7 are derived for mS < 2.05 GeV. These bounds set stringent limits on the existence of such exotic particles.