Mainz 2004 – wissenschaftliches Programm

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T: Teilchenphysik

T 506: Schwache Wechselwirkung II

T 506.10: Vortrag

Mittwoch, 31. März 2004, 18:30–18:45, HS VII

Evidence for a Narrow State at M=1528 MeV at HERMES — •Wolf-Dieter Nowak — DESY, D-15738 Zeuthen, Platanenalle 6

Evidence for a narrow baryon state is found at HERMES in quasi-real photoproduction on a deuterium target in the invariant mass distribution of the p K_s⁰ system, with the Kaon decaying into two charged pions. A peak is observed at 1528 MeV with statistical and systematic uncertainty each being 2 MeV. The width of the peak is dominated by the experimental resolution of 7.2 MeV. Depending on the backgroud model, the naive statistical significance ranges from 4.7 to 9.0 σ. This state may be interpreted as the predicted S=+1 exotic Θ⁺ pentaquark baryon.