H-dibaryon search via Xi(-) capture on the deuteron - art. no. 035206

A search for the H dibaryon has been conducted at the Brookhaven National L aboratory 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 slow ed in degraders and those most likely to stop in an adjacent liquid-deuteri um target were tagged by silicon detectors. Monoenergetic neutrons were sou ght as the signature for H formation in (Xi (-),d)(atom)-->H+n. The experim ent was designed for optimal sensitivity to a loosely-bound H. complementin g recent (K-,K+) measurements on nuclear targets. In addition, the experime nt's sensitivity was independent of lifetime and of decay modes of the H. N o 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 s imilar to 100 MeV of binding and are compared with a corresponding theoreti cal prediction.