We study scalar, pseudoscalar, vector, and axial-vector mesons with non-strange and strange quantum numbers in the framework of a linear sigma model with global chiral U (N f )L × U (N f )R symmetry. We perform a global fit of meson masses, decay widths, as well as decay amplitudes. The quality of the fit is, for a hadronic model that does not consider isospin-breaking effects, surprisingly good. We also investigate the question whether the scalarqq states lie below or above 1 GeV and find the scalar states above 1 GeV to be preferred asqq states. Additionally, we also describe the axial-vector resonances asqq states.

No abstract

We investigate the production of pions in heavy-ion collisions in the energy range of 1 -2 GeV/A. The dynamics of the nucleus-nucleus collisions is described by a set of coupled transport equations of the Boltzmann-Uehling-Uhlenbeck type for baryons and mesons. Besides the N (938) and the ∆(1232) we also take into account nucleon resonances up to masses of 1.9 GeV /c 2 as well as π-, η-and ρ-mesons. We study in detail the influence of the higher baryonic resonances and the 2π-production channels (N N → N N ππ) on the pion spectra in comparison to π − data from Ar + KCl collisions at 1.8 GeV/A and π 0 -data for Au + Au at 1.0 GeV/A. We, furthermore, present a detailed comparison of differential pion angular distributions with the BEVALAC data for Ar + KCl at 1.8 GeV/A. The general agreement obtained indicates that the overall reactions dynamics is well described by our novel transport approach.