Subnuclear Degrees of Freedom in Electromagnetic Interactions in Nuclei

H. Arenhövel

Chinese Journal of Physics

30卷1期（1992 / 02 / 01）

17 - 95

英文

These lectures are devoted to the role of subnuclear degrees of freedom in terms of meson and isobar degrees of freedom as manifest in electromagnetic processes in nuclei. After a brief review of the general structure of the electromagnetic interaction, the gauge conditions and low-energy theorems for the electromagnetic interaction operators are discussed. The various theoretical schemes for incorporating subnuclear degrees of freedom either as effective operators like the pion exchange current or explicitely like the model of nuclear isobar configurations are reviewed. As an important process, the electromagnetic break-up of the deuteron is considered. The different theoretical methods for the calculation of the t-matrix are described and the essential ingredients for the non-relativistic evaluation including the most important relativistic corrections of lowest order are outlined. For specific experiments in photo- and electrodisintegration theoretical results are compared to experimental data. Furthermore, the enhancement of the photonuclear TRK-sum rule by exchange effects is analyzed in detail and, finally, the Compton scattering by the deuteron is studied.