München 2006 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 30: Theorie

HK 30.2: Talk

Wednesday, March 22, 2006, 14:15–14:30, B

In-Medium Change of Four-Quark Condensates: QCD Sum Rule Evaluation for ω-Meson and Nucleon — •Ronny Thomas¹, Sven Zschocke^1,2, and Burkhard Kämpfer^1,3 — ¹Forschungszentrum Rossendorf, Dresden, Germany — ²University of Bergen, Norway — ³TU Dresden, Germany

The evaluation of QCD sum rules for the ω meson inside nuclear matter provides evidence for an in-medium change of four-quark condensates. Conclusions are drawn from the reaction γ + A → A′ + ω with A=Nb,LH₂ measured by the CB-TAPS collaboration pointing to a more than 50 % reduction of the respective condensates at nuclear saturation density. — A catalog of four-quark condensates is presented and generic differences of four-quark condensate structures appearing in QCD sum rules for mesons and baryons are examplified. The in-medium behaviour of the nucleon is revisited in this given framework.