Hadron Structure Studied with the Electromagnetic Probe - from Giant Resonances to Meson Production

The development of theoretical photonuclear physics over the last 40 years is illustrated by a few selected examples highlighting a number of important issues like collective motion in nuclei, the role of subnuclear degrees of freedom, relativity and meson production.Comment: 10 pages latex including 10 figures, invited talk presented at the Symposium on Fundamental Issues in Elementary Matter, Sept. 25-29, 2000, Bad Honnef, German

Construction of Consistent Meson Exchange Currents by Laplace Transform

We propose a new method for the construction of a consistent meson exchange current in $r$-space for the spin-isospin dependent central and tensor part of phenomenological nucleon-nucleon potentials by using a Laplace transformation, which allows the representation by a finite number of Yukawa functions. This method is applied to the Paris and the recent Argonne $V_{18}$ potentials. Results are presented for electrodisintegration of the deuteron near threshold.Comment: 13 pages Revtex including 9 figures, final version accepted for publication in EPJA (one figure and discussion added

The Role of Meson Retardation in Deuteron Photodisintegration above Pion Threshold

Photodisintegration of the deuteron above $\pi$ threshold is studied in a coupled channel approach including $N \Delta$ and $\pi d$ channels with consideration of pion retardation in potentials and exchange currents. A much improved description of total and differential cross sections in the energy region between $\pi$ threshold and 400-450 MeV is achieved. With respect to polarization observables, the description of the linear photon asymmetry and the proton polarization remains problematic.Comment: 26 pages revtex including 25 figure

Polarization observables in elastic electron deuteron scattering including parity and time reversal violating contributions

The general formalism for polarization observables in elastic electron deuteron scattering is extended to incorporate parity and time reversal violating contributions. Parity violating effects arise from the interference of $\gamma$ and $Z$ exchange as well as from the hadronic sector via a small parity violating component in the deuteron. In addition we have allowed for time reversal invariance violating contributions in the hadronic sector. Formal expressions for the additional structure functions are derived, and their decomposition into the various multipole contributions are given explicitly.Comment: 34 pages Revte

Photonuclear effect in heavy deformed nuclei

The theory of Raman scattering is extended to include electric-quadrupole radiation. The results obtained are used to compute the elastic and Raman scattering cross sections of heavy deformed nuclei. The dipole and quadrupole resonances are described by a previously developed theory which includes surface vibrations and rotations. The computed cross sections are compared with experimental data for all those nuclei where both absorption and scattering cross sections are available. Some discrepances still exist in certain details; however, the over-all agreement between theory and experiment is very good

Complete Sets of Polarization Observables in Electromagnetic Deuteron Break-up

For deuteron photo- and electrodisintegration the selection of complete sets of polarization observables is discussed in detail by applying a recently developed new criterion for the check of completeness of a chosen set of observables. The question of ambiguities and their resolution by considering additional observables is discussed for a numerical example, for which the role of experimental uncertainties is also investigated. Furthermore, by inversion of the expressions of the observables as hermitean forms in the $t$-matrix elements a bilinear term of the form $t_{j'}^*t_j$ can be given as a complex linear form in the observables from which an explicit solution for $t_j$ in terms of observables can be obtained. These can also be used to select sets of observables for the explicit representation of the $t$-matrix.Comment: 37 pages revte