Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 30: Elektromagnetische und hadronische Proben V

HK 30.5: Talk

Wednesday, March 19, 2003, 15:15–15:30, B

Σ ⁺-Production at COSY-TOF - Search for an Exotic Pentaquark State (Z ⁺)^* — •M. Wagner, W. Eyrich, M. Fritsch, L. Pinna, W. Schroeder, F. Stinzing, and S. Wirth — Physikalisches Institut, Universität Erlangen-Nürnberg

Within the framework of the hyperon measurement program in nucleon-nucleon collisions at the Time-Of-Flight spectrometer COSY-TOF the reaction pp → K⁰ Σ ⁺ p is being investigated in detail alongside the Λ production channel. The verification of observables in different hyperon production channels is of importance for testing model calculations. The complete geometrical reconstruction of the ejected particles is realized using the Erlangen start detector which has been developed to measure reactions with delayed charged decays. In combination with the endcap detector this system ensures the reconstruction of both the primary tracks and the secondary vertex of the K _s⁰ using two scintillating fibre hodoscopes. To detect the Σ ⁺ hyperon with its short decay length a double sided silicon microstrip detector is applied very close to the target. Data have been taken at beam momenta of 2.85, 2.95 and 3.2 GeV/c. In this talk the analysis methods - particularly the separation of background events - are presented together with total cross sections and first differential observables. The influences of N^* resonances and final state interaction are discussed, as well as the search for a possible exotic pentaquark state (Z⁺). Moreover, first preliminary results of the recent measurement at 3.3 GeV/c are presented.

0.5ex* supported by BMBF and Forschungszentrum Jülich