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RESEARCH PRODUCT

Antiproton-proton annihilation in-flight

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This is an overview of the preliminary results of\(\bar pp\) annihilation at incident\(\bar p\) momenta of 600, 1200 and 1940 MeV/c(*). The data was taken at LEAR with the Crystal Barrel Detector (E. Akeret al.:Nucl. Instrum. Methods A,321, 108 (1992)). In the two pseudoscalar final states seven different channels are observable and their angular distributions are measured. They are compared to older data, if existent, and are found to be equal within the experimental errors. In the three-meson final states, an overview of the already examined final states is given. Striking signals in the Dalitz plots and invariant-mass projections for a set of final states are observed. In the final states ηηπ0 and ηηη a signal ηη with the invariant mass of 1480 MeV/c2 and a width of aboutΓ≈≈70 MeV/c2 is visible. In the final-state ωηπ0 a signal in the ωη invariant-mass spectrum at 1680 MeV/c2 with a widthΓ≈150 MeV/c2 is observed. Finally, in the final-state ωωπ0 two visible structures in the Dalitz plot are detected at 1600 MeV/c2 (Γ≈90 MeV/c2) and 1900 MeV/c2 (Γ≈150 MeV/c2).