Studies on the structure of the free and bound nucleon using the real-photon facilities at MAX (Lund), MAMI (Mainz) and ELSA (Bonn)
✍ Scribed by M. Schumacher
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 249 KB
- Volume
- 629
- Category
- Article
- ISSN
- 0375-9474
No coin nor oath required. For personal study only.
✦ Synopsis
Recent results on Compton scattering and meson photoproduction by nucleons and nuclei obtained with quasimonochromatic real photons and their importance for the understanding of the structure of the free and bound nucleon are outlined. The effective mass of nucleons in a nucleus manifests itself in enhancements of nuclear Thomson scattering and giant-resonance strengths. The electromagnetic polarizabilities probe possible in-medium structure changes of nucleons. Compton scattering by nucleons leads to conclusions on photon couplings of nucleon resonances and on the two-photon coupling of the a meson. Nuclear Compton scattering in the A range leads to dramatic deviations from predictions based on conventional A-hole considerations. The neutron-proton ratio of cross sections for r/ meson photoproduction proved to be 2/3 throughout the energy range from threshold to 1.15 GeV. This makes direct photon-quark coupling a possible mechanism.
*on behalf of the collaborations at MAX, MAMI and ELSA, supported by Deutsche Porschungsgemeinschaft (SFB 201 and contract SCHU 222), DAAD and BMBF