SEARCHES FOR EXOTIC BARYONS IN EXPERIMENTS EMPLOYING A 70-GEV PROTON-BEAM AND OTHER MEASUREMENTS WITH THE SPHINX FACILITY

Results obtained at the first stage of experiments with the SPHINX fac ility are presented in this review. Several diffractive production pro cesses in a 70-GeV proton beam from the IHEP accelerator were studied in these experiments. Evidence for new baryon states with masses in ex cess of 2 GeV were obtained in the effective mass spectra of the hyper on-kaon system formed in the coherent reactions p + C --> [Sigma(1385) K-0(+)] + C and p + C --> [Sigma(0)K(+)] + C. Unusual features of thes e massive states (relatively small decay widths and large branching ra tios for decays with strange particles in final states) make them seri ous candidates for cryptoexotic pentaquark baryons with hidden strange ness. Preliminary data on nonperipheral p + N interactions with transv erse momenta squared higher than 0.3 GeV2 [mass spectra M(Sigma(0)K(+) ), M(p eta), and M(p eta')] are also presented in this review, as well as recent data obtained by studying the OZI selection rule in hadroni c processes with initial pions and protons.