EPJ

2021 Impact factor 3.131
EPJ A - Hadrons and Nuclei
Hadrons and Nuclei
Eur. Phys. J. A 5, 409-416

New data on the $p + N \to [\Sigma^0K^+] + N$ reaction at Ep = 70 GeV and the search for exotic baryons

The SPHINX Collaboration (IHEP-ITEP)

S.V. Golovkin1 - A.P. Kozhevnikov1 - V.P. Kubarovsky1 - V.F. Kurshetsov1 - L.G. Landsberg1 - V.V. Molchanov1 - V.A. Mukhin1 - S.V. Petrenko1 - V.A. Senko1 - D.V. Vavilov1 - V.A. Victorov1 - V.Z. Kolganov2 - G.S. Lomkatsi2 - A.F. Nilov2 - V.T. Smolyankin2

1 State Research Center, Institute for High Energy Physics, Protvino, Russia
2 State Research Center, Institute of Theoretical and Experimental Physics, Moscow, Russia

Received: 28 April 1999 Communicated by V.V. Anisovich

Abstract
New data for the diffractive reaction $p+N \rightarrow [\Sigma^oK^+]+N$at Ep=70 GeV were obtained with partially upgraded SPHINX setup. The data are in a good agreement with the results of our previous study of this reaction. In the mass spectrum $M(\Sigma^oK^+)$ a structure at the threshold region with a mass $\sim$1810 MeV and a distinct X(2000) peak with $M=1989\pm6$ MeV and $\Gamma=91\pm20$ MeV are observed. Unusual features of the massive X(2000) state (narrow decay width, anomalously large branching ratio for the decay channel with strange particle emission) make it a serious candidate for cryptoexotic pentaquark baryon with hidden strangeness $\vert qqqs\bar s\gt$. We also present new results on the narrow threshold structure X(1810) with $M=1807\pm7$ MeV and $\Gamma=62\pm19$ MeV which is produced in the region of very small P2T<0.01 GeV2. The possibility of the Coulomb production mechanism for X(1810) is discussed.

PACS
13.85.Fb Inelastic scattering: two particle find state - 25.40.Ve Other reactions above meson production thresholds (energies >400 MeV)

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