arXiv subjects
Publications and source records attributed to Th. A. Rijken.
A review is given of the various Nijmegen potentials. Special attention is given to some of the newest developments, such as the extended soft-core model, the high-quality potentials, and the Nijmegen optical potentials for NN.
We present results of the Nijmegen partial-wave analyses of all NN scattering data below Tlab = 500 MeV. We have been able to extract for the first time the important np phase shifts for both I = 0 and I = 1 from the np scattering data alone. This allows us to study the charge independence breaking between the pp and np I = 1 phases. In our analyses we obtain for the pp data chi^2_{min}/Ndf = 1.13 and for the np data chi^2_{min}/Ndf = 1.12.
We report on the progress of the construction of the extended soft-core (ESC) Nijmegen potential. Next to the standard one-boson-exchange parts, the model includes the pion-meson-exchange potentials due to the parallel and crossed-box diagrams, as well as the one-pair and two-pair diagrams, vertices for which can be identified with similar interactions appearing in chiral-symmetric Lagrangians. Although the ESC potential is still under construction, it already gives an excellent description of all $N\!N$ scattering data below 350 MeV with $χ^{2}/{\rm datum}=1.3$.
A partial-wave analysis of all antiproton-proton scattering data below 925 MeV/c antiproton laboratory momentum is presented. The method used is adapted from the Nijmegen phase-shift analyses of pp and np scattering data. The Nijmegen 1993 antiproton-proton database, consisting of 3646 antiproton-proton scattering data, is presented and discussed. The best fit to this database results in chi^2_min/Ndata = 1.043. The pseudovector coupling constant of the charged pion to nucleons is determined to be (f_c)^2 = 0.0732(11) at the pion pole, where the error is statistical.
Invited talk given at the NAN '93 Conference in Moscow, Russia, sept 1993. A review is given of the different ways to describe pbarp scattering. Next the Nijmegen partial wave analyses of the pbarp data as well as the corresponding Nijmegen NbarN database are discussed. These partial wave analyses are finally used as a tool to construct a better NbarN potential model and also to clarify questions raised in the literature.
After a short survey of some topics of interest in the study of baryon-baryon scattering, the recent Nijmegen energy dependent partial wave analysis (PWA) of the nucleon-nucleon data is reviewed. In this PWA the energy range for both pp and np is now 0 < Tlab < 350 MeV and a chi^2_{d.o.f.}=1.08 was reached. The implications for the pion-nucleon coupling constants are discussed. Comments are made with respect to recent discussions around this coupling constant in the literature. In the second part, we briefly sketch the picture of the baryon in several, more or less QCD-based, quark-models that have been rather prominent in the literature. Inspired by these pictures we constructed a new soft-core model for the nucleon-nucleon interaction and present the first results of this model in a chi^2 -fit to the new multi-energy Nijmegen PWA. With this new model we succeeded in narrowing the gap between theory and experiment at low energies. For the energies Tlab = 25-320 MeV we reached a record low chi^2_{p.d.p.} = 1.16. We finish the paper with some conclusions and an outlook describing the extension of the new model to baryon-baryon scattering.
Invited talk presented by the first author at the XIVth European Conference of Few-Body Problems in Physics, Amsterdam, August 23-28, 1993