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Abstract.The results of E-190 experiment (project Thermalization) with 50 GeV proton beam irradiation of SVD-2 setup are presented. MC simulation has shown the linear dependence of number of photons detected in electromagnetic calorimeter and the average number of neutral pions. Multiplicity distribution of neutral pion, N 0 , for total number of particles in the event, N tot = N ch + N 0 , are obtained with corrections on the setup acceptance, triggering and efficiency of the event reconstruction. The scaled variance of neutral pion fluctuations, ω = D/ < N 0 >, versus total multiplicity is measured. The fluctuations increase at N tot > 18. According to quantum statistics models this behavior can indicate a pion condensate formation in the high pion multiplicity system. This effect has been observed for the first time.

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the Θ + -baryon, in a pK 0 s decay mode at 70 GeV /c on IHEP accelerator. The reaction pA → pK 0 s + X with a limited multiplicity was used in the analysis. The pK 0 s invariant mass spectrum shows a resonant structure with M = 1526 ± 3(stat.) ± 3(syst.) M eV /c 2 and Γ < 24 M eV /c 2 . The statistical significance of this peak was estimated to be of 5.6 σ. The mass and width of the resonance is compatible with the recently reported Θ + -baryon with positive strangeness which was predicted as an exotic pentaquark (uudds) baryon state. The total cross section for Θ + production in pN-interactions for XF ≥ 0 was estimated to be (30 ÷ 120) µb and no essential deviation from A-dependence for inelastic events (∼ A 0.7 ) was found.