Bochum 2009 – scientific programme

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HK: Fachverband Hadronen und Kerne

HK 34: Hadron Structure and Spectroscopy I

HK 34.6: Talk

Tuesday, March 17, 2009, 18:00–18:15, H-ZO 20

Radiative pion photoproduction in the region of the Delta(1232) resonance — •Evangeline J Downie — Institut fuer Kernphysik, Johannes Gutenberg Universitaet, Mainz, Germany

The Delta(1232) is perhaps the best-studied resonance in the nucleon excitation spectrum. From these studies, we have learned much about the nucleon-delta transition. However we have learned very little about the properties of the Delta itself, due to the exceedingly short lifetime of this strongly-decaying resonance. The Magnetic Dipole Moment of the Delta(1232) is predicted by many theories and models, ranging from the chiral limit to Lattice QCD (LQCD) calculations at unphysically high quark mass values. The experimental determination of this quantity in the physical mass region would provide both a strong test of the many models which operate within this region and an important constraint on the extrapolation between theoretical predictions at the chiral and LQCD quark mass limits.

The A2 Collaboration, of the Institut fuer Kernphysik at Johannes Gutenberg Universitaet in Mainz, Germany, are studying this property using radiative pion photo production. The experiment makes use of the tagged photon beam, produced by the Glasgow Photon Tagging Spectrometer from the MAMI electron beam. The reaction products, passing out of the liquid Hydrogen target, are detected using the powerful, large acceptance spectrometer combination of the Crystal Ball and TAPS. The talk will cover the method, data analysis and latest results from this experiment.