In the experiments at the SPHINX facility in 70 GeV proton beam of the IHEP accelerator the coherent diffractive production reactions on carbon nucleip+C→ [∑(1385)0K++C andp+C→[Σ0K+]+C were investigated. The evidences for new baryon states were obtained in the study of hyperon-kaon effective mass spectra in these two reactions:X (2050) with massM=(2052±6) MeV and width Γ=(35 −35 +22 ) MeV inM[∑(1385)0K+] andX(2000) withM=1999±6 MeV and Γ=91±17 MeV inM[Σ0K+]. The unusual features of these massive states (small enough decay widths, anomalously large branching ratios for decays with strange particles emission) make them very serious candidates for cryptoexotic pentaquark baryons with hidden strangeness.

The radiative decayη′→π+π−γ has been studied with the statistics of ≃2000 events. Different ways of describingmππ distribution are considered. It is shown that if the dominating contribution to this process is made by the decay channel η′→ργ, then the generally accepted ways of describing the ρ peak do not agree with experimental data.