Direct Observation of Sequential Weak Decay of a Double Hypernucleus

Abstract

We have studied stars in nuclear emulsion due to the capture at rest of the Ξ- hyperons produced in the (K-, K+) reaction. The sequential weak decay of a double hypernucleus (nucleus with S=-2) has been directly observed. The double hypernucleus is assigned as either ^{10}_{\Lambda\Lambda}Be or ^{13}_{\Lambda\Lambda}B. This assignment excludes the existence of the H dybaryon lighter than 2203.7+-0.7 MeV/c^2