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HK: Physik der Hadronen und Kerne

HK 9: Elektromagnetische und Hadronische Proben

HK 9.3: Vortrag

Freitag, 4. März 2005, 17:15–17:30, TU MA004

Observation of an excited neutral hyperon state in pp collisions^* — •Izabella Zychor¹, Vladimir Koptev², Markus Büscher³, Michael Hartmann³, Irakli Keshelashvili³, Vera Kleber⁴, Rudiger Koch³, Sigfried Krewald³, Yoshikazu Maeda³, Siergiej Mikirtichyants², Michail Nekipelov^2,3, and Hans Ströher³ — ¹The Andrzej Sołtan Institute for Nuclear Studies, 05400 Świerk, Poland — ²High Energy Physics Department, Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia — ³Institut für Kernphysik, Forschungszentrum Jülich, 52425 Jülich, Germany — ⁴Institut für Kernphysik, Universität zu Köln, 550937 Köln, Germany

The reaction pp → pK⁺ Y^0* → pK⁺π^±X^∓ has been studied with the ANKE spectrometer at COSY Jülich in order to investigate heavy hyperon production. The momentum of the proton beam, incident on a hydrogen cluster-jet target, was 3.65 GeV/c. Protons, kaons and pions were identified with the ANKE detector system consisting of range telescopes, scintillation counters and multi–wire proportional chambers. The missing mass spectra MM(pK⁺) have been analyzed for both positive and negative charge final states and compared with extensive Monte Carlo simulations. Indications for a neutral excited hyperon resonance Y^0*(1480) have been found. Consistent results for its mass and width as well as a production cross section were obtained for both final states. Experimental details, analysis procedure and a possible interpretation of this state will be discussed.

^* supported by FZJ, BMBF, DFG