Köln 2004 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 44: Electromagnetic and Hadronic Probes VII
HK 44.2: Gruppenbericht
Donnerstag, 11. März 2004, 17:00–17:30, B
Hyperonproduction and the search for a pentaquark state at COSY-TOF* — •Wolfgang Eyrich — Physikalisches Institut der Universität Erlangen-Nürnberg
The associated strangeness production in elementary nucleon-nucleon induced reactions is studied exclusively using the spectrometer COSY-TOF. The complete reconstruction of all charged particle tracks allows the extraction of total and differential cross sections and Dalitz plots as well. The design of the COSY apparatus provides the opportunity to cover the full phase space of the reactions from threshold up to the COSY energy limit. Especially the reaction channel pp → K+Λ p was investigated recently in detail with high statistics and delivered precise results which show strong N* and FSI contribution. Alongside Λ-production, the production of Σ-hyperons is a further point of interest within the associated strangeness production. Both production channels, Σ0 and Σ+, have been measured. Moreover the reaction channels pp → K0 Σ+ p and pp → K+ Σ+ n are of high interest due to a possible exotic pentaquark resonance which might contribute to the production mechanisms.
This talk will focus on the recent results of the TOF experiment on Λ- and Σ-production, especially discussing the strong energy-dependent influence of the 1650 and 1710 N* resonances in the Λ-production channel. Moreover the status of the search for an exotic pentaquark state is presented, where the preliminary analysis of the pp → K0 Σ+ p data at a beam momentum of 2.95 GeV/c show evidence for a narrow enhancement in the K0 p invariant mass spectrum around 1530 MeV/c.
*Supported by BMBF and FZ Juelich