Köln 2004 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 47: Heavy Ions V

HK 47.1: Gruppenbericht

Donnerstag, 11. März 2004, 16:30–17:00, E

Dilepton production in elementary and heavy ion collisions at intermediate energies — •Christian Fuchs¹, Amand Faessler¹, Mikhail Krivoruchenko^1,2, and Boris Martemyanov^1,2 — ¹Institut für Theoretische Physik der Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany — ²Institute for Theoretical and ExperimentalPhysics, B. Cheremushkinskaya 25, 117259 Moscow, Russia

We present a unified description of the vector meson and dilepton production in elementary and in heavy ion reactions. The production of vector mesons (ρ,ω) is described via the excitation of nuclear resonances (R). The theoretical framework is an extended vector meson dominance model (eVMD). The resonance model is successfully applied to the ω production in p+p reactions and to the dilepton production in elementary reactions (p+p, p+d). However, when the model is applied to heavy ion reactions in the BEVALAC/SIS energy range the experimental dilepton spectra measured by the DLS Collaboration are significantly underestimated at small invariant masses. As a possible solution of this problem the destruction of quantum interference in a dense medium is discussed. A decoherent emission through vector mesons decays enhances the corresponding dilepton yield in heavy ion reactions. In the vicinity of the ρ/ω-peak the reproduction of the data requires further a substantial collisional broadening of the ρ and in particular of the ω meson.