OBSERVATION OF SUBTHRESHOLD DOUBLE STRANGENESS PRODUCTION IN (P)OVER-BAR ANNIHILATIONS ON XE NUCLEI - SEARCH FOR STABLE H-DIBARYON

The double strangeness production has been observed in two final state s of annihilation of antiprotons at momentum less than 0.9 GeV/c on Xe nuclei: K+K+X (8 events) and K+K0LAMBDAX (6 events). The probabilitie s of the reaction pXeBAR --> K+K+X vary from 2. 10(-5) (at rest) up to 7. 10(-5) (in flight). The reaction pXeBAR --> K+K0LAMBDAX is observe d only in flight with probability 3 . 10(-4). The properties of the ob served reactions are similar to those resulting from the cascade proce ss with production of XI hyperon: pNBAR --> KK*BAR, K* --> Kpi, K*NBA R --> XIK, XIN --> LAMBDALAMBDA. The new upper limit on the production probability of the stable H(S = -2) dibaryon in the reaction pXeBAR - -> K+K+H(H --> SIGMA-p)X was obtained to be < 2 . 10(-5) (90%C.L.).