München 2006 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 23: Elektromagnetische und Hadronische Sonden

HK 23.1: Vortrag

Dienstag, 21. März 2006, 17:00–17:15, G

Search for exotic pentaquark and hexaquark candidates in — •Josef Pochodzalla — Inst. für Kernphysik, Universität Mainz, 55099 Mainz

During the last years twelve experimental groups have reported evidence for a narrow baryonic resonance in the KN channel at a mass of about 1540 MeV/c². We report on a high-statistics search for the Θ(1540)⁺ resonance in the K_Sp decay channel, produced in Σ⁻-nucleus collisions at 340 GeV/c. No evidence for this resonance was found in our sample of 13 million K_s⁰ → π⁺π⁻ decays above background [1]. Already previously we have reported a null-result when searching for the exotic Φ^–(1860) pentaquark state [2].

We also searched for the recently reported Λ p resonance at ≃ 2300MeV/c², using our sample of 12 million identified Λ decays. We found no indication of such a resonance.

In the diffractive region (x_F >0.8) we do however observe a broad (Γ≃ 90MeV/c²) resonance-like structure in the K_Sp channel at a mass of ≃ 1750MeV/c², which is possibly related to known Σ^* resonances.

Work supported by BMBF under contract 06MZ177.

[1] WA89 collaboration, Phys. Rev. C 72, 055201 (2005)
[2] WA89 collaboration, Phys. Rev. C 70, 022201(R)