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HK: Physik der Hadronen und Kerne

HK 13: Poster Session: Heavy Ions

HK 13.9: Poster

Dienstag, 12. März 2002, 10:30–12:45, Foyer Chemie

The role of three-body collisions in φ mesonproduction processes near threshold in heavy-ion reactions — •H.W. Barz¹, B. Kämpfer¹, M. Zetenyi², and Gy. Wolf² — ¹FZ Rossendorf, D-01314 Dresden — ²KFKI Budapest, H-1525 Budapest

The amplitude of subthreshold φ meson production is calculated using dominant tree-level diagrams for three-body collision. It is shown that the production can overwhelmingly be described by two consecutive two-step processes, i.e. the cross section factorises in two sub-cross-sections with an intermediate on-shell particle. As a consequence to desribe the production of heavy mesons within transport models all intermediate particles have to be included in the calculations. The effect is demonstrated in calculating φ production in heavy-ion collisions at bombarding energies around 2 GeV per nucleon as recently measured by the FOPI collaboration. Including elementary ρ−N, ρ−Δ and π−ρ collisions the calculated production rates increase by about a factor of three compared to earlier calculations which do not include these channels. Momentum spectra of φ mesons and dilepton spectra which are accessible in future HADES and FOPI experiments are given.