Bochum 2009 – scientific programme

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HK: Fachverband Hadronen und Kerne

HK 34: Hadron Structure and Spectroscopy I

HK 34.5: Talk

Tuesday, March 17, 2009, 17:45–18:00, H-ZO 20

Photoproduction of pion pairs off ⁷Li — •Yasser Maghrbi — Department of Physics, University of Basel

The photoproduction of π⁰ π⁰− and π⁰ π^+/−− pairs off ⁷Li has been studied at the Mainz MAMI accelerator for photon energies from threshold to 830 MeV. The experiment used the Glasgow photon tagging device and the combined Crystal Ball/TAPS electromagnetic calorimeter. The experiment was motivated by the much discussed in-medium properties of the σ-meson. Previous results indicated a shift of the strenght to small invariant masses for π⁰ π⁰ but not for π⁰ π^+/−. However, comparisons to transport model calculations have shown that final state interaction (FSI) can produce similar effects. Therefore, in a new series of experiments with improved statistical quality, data was also taken for the light nucleus ⁷Li, serving as a better reference point for FSI. Preliminary total cross sections and invariant mass distributions will be presented.

Supported by Schweizerischer Nationalfond, DFG, and EU/FP6.