Observation of narrow baryon resonance decaying into pKs0pK^0_s in pA-interactions at 70GeV/c70 GeV/c with SVD-2 setup

SVD-2 experiment data have been analyzed to search for an exotic baryon state, the $\Theta^+$-baryon, in a $pK^0_s$ decay mode at $70 GeV/c$ on IHEP accelerator. The reaction $pA \to pK^0_s+X$ with a limited multiplicity was used in the analysis. The $pK^0_s$ invariant mass spectrum shows a resonant structure with $M=1526\pm3(stat.)\pm 3(syst.) MeV/c^2$ and $\Gamma < 24 MeV/c^2$. The statistical significance of this peak was estimated to be of $5.6 \sigma$. The mass and width of the resonance is compatible with the recently reported $\Theta^+$- baryon with positive strangeness which was predicted as an exotic pentaquark ($uudd\bar{s}$) baryon state. The total cross section for $\Theta^+$ production in pN-interactions for $X_F\ge 0$ was estimated to be $(30\div120) \mu b$ and no essential deviation from A-dependence for inelastic events $(\sim A^{0.7})$ was found.Comment: 8 pages, 7 figures, To be submitted to Yadernaya Fizika. v3-v5 - Some references added, minor typos correcte

Comparison of the In-plane Thermal and Electrical Conductivities and Transverse Pull Strengths of Various Pyrolytic Graphite Materials

Different pyrolytic graphite materials were produced varying the annealing parameters such as temperature, pressure and time. These variations should alter the product properties in a systematic way. The coefficient of in-plane thermal conductivity, C_KT, the coefficient of electrical conductivity, $\sigma$ and the pull strength S of these samples were measured. Results for the different materials and correlations are reporte

Neutral pion number fluctuations at high multiplicity in pp-interactions at 50 GeV

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, N0, for total number of particles in the event, Ntot = Nch + N0, are obtained with corrections on the setup acceptance, triggering and efficiency of the event reconstruction. The scaled variance of neutral pion fluctuations, ω = D/ , versus total multiplicity is measured. The fluctuations increase at Ntot > 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