Search for a Stable Six-Quark State at BABAR

Abstract

Recent investigations have suggested that the six-quark combination u u d d s s 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 → S ¯ Λ ¯ Λ decays based on a sample of 90 × 1 0 6 Υ ( 2 S ) and 110 × 1 0 6 Υ ( 3 S ) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined Υ ( 2 S , 3 S ) → S ¯ Λ ¯ Λ branching fraction in the range ( 1.2 - 1.4 ) × 1 0 − 7 are derived for m S < 2.05 GeV . These bounds set stringent limits on the existence of such exotic particles.