# Search for a Stable Six-Quark State at BABAR

22 February 2019

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 $\Upsilon \to S\overline{\Lambda }\overline{\Lambda }$ decays based on a sample of $90×1{0}^{6}\Upsilon \left(2S\right)$ and $110×1{0}^{6}\Upsilon \left(3S\right)$ decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined $\Upsilon \left(2S,3S\right)\to S\overline{\Lambda }\overline{\Lambda }$ branching fraction in the range $\left(1.2–1.4\right)×1{0}^{-7}$ are derived for ${m}_{S}<2.05\text{}\text{}\mathrm{GeV}$. These bounds set stringent limits on the existence of such exotic particles.

Published in: Physical Review Letters 122 (2019)