H-dibaryon search via Ξ- capture on the deuteron

A search for the H dibaryon has been conducted at the Brookhaven National Laboratory AGS, using a 1.8 GeV/C K- beam. Xi (-) hyperons were produced in a liquid-hydrogen target via the reaction K-+p-->K-. The hyperons were slowed in degraders and those most likely to stop in an adjacent liquid-deuterium target were tagged by silicon detectors. Monoenergetic neutrons were sought as the signature for H formation in (Xi (-),d)(atom)-->H+n. The experiment was designed for optimal sensitivity to a loosely-bound H. complementing recent (K-,K+) measurements on nuclear targets. In addition, the experiment's sensitivity was independent of lifetime and of decay modes of the H. No statistically significant evidence for H formation was seen. Upper limits on the branching ratio for H formation in the above reaction have been set in a mass range extending from slightly above Lambda Lambda threshold to similar to 100 MeV of binding and are compared with a corresponding theoretical prediction.