H particles, double hyper nuclei (KEK-E176)

The KEK-E176 carried out by 14 Japanese institutes and 5 universities in ROK is the composite experiment of emulsion and counter for the purpose of studying on the formation, structure and decay of H particles and lambda lambda nuclei. As compared with the experiment in the past, with the reliability of more than 103 in statistics, the analysis of p(K-, K+)Ξ- reaction was carried out. At present, about 80 % of the analysis for the K+ momentum of more than 1.0 GeV/C has been finished. At Ξ- absorption point, the exploration of the formation and decay of lambda nuclei and lambda lambda nuclei was carried out, and the reactions of formation and decay of two lambda nuclei, light lambda lambda nuclei and heavy lambda lambda nuclei were detected. The exploration of the formation and decay of H particles at absorption point is in progress now. At (K-, K+) reaction point, the exploration of H particles by K-+(pp)→H+K+ was finished, and the upper limit of the formation of H particles for quasi-free xi- formation cross section was determined. As for the formation of lambda lambda nuclei in the reaction which is not accompanied by Ξ- candidate, two cases of the candidate were detected. The experiment and the results are reported. (K.I.)