Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 47: Heavy Ions V

HK 47.5: Talk

Thursday, March 11, 2004, 18:00–18:15, E

The N N → N Δ cross section in nuclear matter — •Alexei Larionov and Ulrich Mosel — Institut für Theoretische Physik, Universität Giessen, 35392 Giessen, Germany

We present calculations of the N N → N Δ cross section in nuclear matter within the one-pion exchange model taking into account pion collectivity, vertex renormalization by the contact nuclear interactions and Dirac effective masses of the baryons due to coupling with the scalar σ field. Introducing the Dirac effective masses leads to an in-medium reduction of the cross section. The experimental data on pion multiplicities from the collisions of Ca+Ca, Ru+Ru and Au+Au at 0.4÷1.5 A GeV (GSI Darmstadt, FOPI Collaboration) are well described by Boltzmann-Uehling-Uhlenbeck (BUU) calculations with the in-medium cross section.
Work supported by GSI.