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In oder to study proton-proton bremsstrahlung moving towards the elastic limit, a detection system, consisting of Plastic-ball and SALAD, was set up and an experiment at 190 MeV incident beam energy was performed. Here, the experimental setup and the data analysis procedure along with some results obtained in the measurement are discussed.

The external-field QCD Sum Rules method is used to evaluate the coupling constants of the light-isoscalar scalar meson (``\sigma'' or \epsilon) to the \Lambda, \Sigma, and \Xi baryons. It is shown that these coupling constants as calculated from QCD Sum Rules are consistent with SU(3)-flavor relations, which leads to a determination of the F/(F+D) ratio of the scalar octet assuming ideal mixing: we find \alpha_s \equiv F/(F+D)=0.55. The coupling constants with SU(3) breaking effects are also discussed., Comment: 15 pages, 8 figures, to be published in Phys. Rev. C

The present status of the theory for nucleon-nucleon bremsstrahlung is outlined. Microscopic calculations are compared with the experimental data for selected kinematics of the 190 MeV KVI pp gamma experiment. Large discrepancies between theory and experiment are observed. The two widely used Soft Photon Models are given as well as a new one which, allows for a more systematic analysis of the bremsstrahlung amplitude.

High-precision data in three-nucleon scattering processes and state-of-the-art few-body calculations have contributed significantly to our present understanding of three-nucleon forces at intermediate energies. This paper discusses in more detail the pd -> He-3 gamma reaction as a probe for electromagnetic currents in the three-nucleon system. Experimental data are reviewed and interpreted by a comparison with Faddeev and coupled-channel calculations from the Bochum-Cracow and Hanover theory groups, respectively.

The QCD Sum Rules method which links the hadronic degrees of freedom with the underlying QCD parameters, serves as a very useful tool to extract qualitative and quantitative information about hadron properties. The QCD sum rules method has been extensively used to investigate the meson-baryon couplings, especially the pseudoscalar meson-nucleon case where the calculations of the pion-nucleon coupling constant reproduce the empirical value fairly well. In this work, the meson baryon coupling constants are analyzed using QCD sum rules method, with an emphasis on the scalar meson-nucleon interactions which play an important role in one boson exchange (OBE) models of nucleon-nucleon (NN) and hyperon-nucleon (YN) interactions. The coupling constants obtained are compared with the results of Nijmegen NN potential model.

A coupled channels analysis, based on the K-matrix approach, is presented for photo-induced kaon production. It is shown that channel coupling effects are large and should not be ignored. The importance of contact terms in the analysis, associated with short range correlations, is pointed out. The extracted parameters are compared with SU(3)-model predictions.

With the combined setup of the Crystal Barrel and TAPS photonspectrometers at ELSA in Bonn we have studied photonuclear reactions on protons and deuterons. From the series of experiments on single and multiple neutral meson emission we concentrate here on the hyperon production off protons and deuterons, and in particular on the K-0 Sigma(+) decay channel. The reaction is characterized by the final state of 6 photons and a forward emitted proton. We report on the first results from this channel.

Two-photon bremsstrahlung in proton-proton scattering is considered with special attention to the influence of a possible dibaryon resonance on the differential cross section.

The nuclear physics relevant to the electric dipole moment (EDM) of the deuteron is addressed. The general operator structure of the P- and T-odd nucleon-nucleon interaction is discussed and applied to the two-body contributions of the deuteron EDM, which can be calculated in terms of P- and T-odd meson-nucleon coupling constants with only small model dependence. The one-body contributions, the EDMs of the proton and the neutron, are evaluated within the same framework. Although the total theoretical uncertainties are sizable, we conclude that, compared to the neutron, the deuteron EDM is competitive in terms of sensitivity to CP violation, and complementary with respect to the microscopic sources of CP violation that can be probed.

The response functions of the radiative capture of a proton by a deuteron has been studied after an experiment done at the KVI with SALAD abd TAPS in 1997. Yet in order to improve the accuracy of the results obtained, and to cover a larger angular region, we have recently performed an other experiment at the KVI, with a deuteron beam of 180 MeV and a liquid-hydrogen target.

We compare a relativistic covariant model for proton-proton bremsstrahlung with new high-quality data from KVI. The agreement in large parts of phase space is satisfactory. However, remarkably large discrepancies are observed for specific kinematic regions. These failures are shown to occur primarily when the final two-nuelcon system has energies less than about 15 MeV.

We study the neutrino emissivity of strongly magnetized neutron stars due to the charged and neutral current couplings of neutrinos to baryons in strong magnetic fields. The leading order neutral current process is the one-body neutrino-pair bremsstrahlung, which does not have an analogue in the zero field limit. The leading order charged current reaction is the known generalization of the direct Urea processes to strong magnetic fields. While for superstrong magnetic fields in excess of 10(18) G the direct Urea process dominates the one-body bremsstrahlung, we find that for fields on the order 10(16) - 10(17) G and temperatures a few times 10(9) K the one-body bremsstrahlung is the dominant process. Numerical computation of the resulting emissivity, based on a simple parametrization of the equation of state of the npe-matter in a strong magnetic field, shows that the emissivity of this reaction is of the same order of magnitude as that of the modified Urea process in the zero field limit.

The electromagnetic moments of the Delta-isobars are of significant interest in hadronic physics. In particular the magnetic (dipole) moments have been investigated, using effective Lagrangian methods or soft-photon amplitudes. Some theoretical issues pertinent to such studies are discussed.

We re-examine the puzzling pi(+) emission from the weak decay of He-4(Lambda) and purpose an explanation in terms of a three-body decay similar to of the virtual Sigma(+). Such a resolution of the pi(+) decay puzzle is consistent with the calculated Sigma(+) probability in light Lambda hypernuclei as well as the experimentally observed pi(+) energy spectrum and s-wave angular distribution. (C) 1998 Elsevier Science B.V.

The situation in low-energy pion-nucleon scattering is reviewed, using an energy-dependent PWA as a tool. The method and some conclusions of this new PWA of pi N scattering data across the Delta(1232) are summarized. In particular, the "inconsistencies" in the low-energy database are addressed, and the state-of-the-art of the NN pi coupling constant and of the pi N sigma-term is discussed.

Several topics in pion-nucleon scattering at low energies are addressed. First, we review the predictions of chiral symmetry for the near-threshold region. The pion-nucleon scattering lengths and the Cheng-Dashen theorem with the related issue of the strangeness content of the nucleon are discussed in some detail. Finally, the status of the scalar mesons and the relevance of the pomeron and the concept of duality for pion-nucleon dynamics is pointed out.