Bonn 2010 – wissenschaftliches Programm
HK 26.8: Vortrag
Dienstag, 16. März 2010, 18:30–18:45, HG IV
Polarization Observables in η-Electroproduction — •Konrad Grießinger — Institut für Kernphysik, Universität Mainz, J.-J.-Becher-Weg 45, 55128 Mainz
The polarization observables of the η-meson are crucial for a better understanding of the structure of the nucleon. In the investigation of nucleon resonances via scattering cross-sections it is rather difficult to extract resonances besides the Δ(1232) due to its overwhelming production rate. When producing η-mesons this problem does not exist, since the η-meson has isospin T=1/2. The Δ-resonances have isospin T=3/2, and therefore cannot be part of the background in η-production. Still, by measuring the cross-section of η-production only a very limited amount of information can be extracted, because the S11(1535)-resonance strongly dominates the cross-section. Thus the polarization observables of the η must be studied in order to examine the role of other resonances.
In this experiment of the A1-Collaboration at MAMI the polarization observables of the η-meson in electroproduction were investigated. Two settings were measured, both at ε=0.718, Q2=0.1 GeV2, φ=0, one at Θ=90∘, W=1525 MeV, the other at Θ=120∘, W=1500 MeV.
Preliminary results of our recent measurements will be presented and will be compared to theory and previous data.