Search

A brief review of the pion-nucleon sigma-term is given. Aspects of both chiral perturbation theory and phenomenology are discussed., Comment: 6 pages, 9th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon, 26-31 July, 2001, Washington D.C

Most of the data from the meson factories were available only after the $\pi N$ partial wave analysis of Koch and Pietarinen was published over 20 years ago. Since then, both the experimental precision and the theoretical framework have evolved a lot as well as the computing technology. Both the new and the earlier data are to be analysed by a highly modernised version of the earlier approach. Especially the propagation of the measurement errors in the analysis will be considered in detail, visualisation tools will be developed using the Python/Tkinter combination, and the huge data base of experiments will be handled by MySQL., Comment: 6 pages, 1 figure. For the proceedings of Menu 2001, Washington DC, Jul. 26-31, 2001

We consider sigma-terms in $\pi\pi$, $\pi N$ and $K N$ scattering. While the state of the art in $\pi\pi$ is in principle crystal clear, the kaon-nucleon case is largely unexplored. The pion-nucleon system is in-between. We propose a list of topics to be investigated in kaon-nucleon scattering, in order to make optimal use of the precision data expected from DEAR., Comment: 10 pages (LaTex). Invited talk given at the Workshop "Physics and Detectors for DAFNE", Frascati, Nov. 16-19, 1999

A brief introduction to different determinations of the piNN coupling constant is given, and some comments on the topics discussed in the working group are made., 6 pages, 3 figures, 8th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon, Zuoz, Switzerland, Aug. 15-21, 1999

A brief discussion of the elastic pion-pion scattering amplitude to two loops in chiral perturbation theory is given. Some technical details of the evaluation of two-loop diagrams are addressed, and results relevant for the pionium decay are presented., 8 pages, 2 figures, Proc. Int. Workshop Hadronic Atoms and Positronium in the Standard Model, Dubna, Russia, May 26-31, 1998

We consider chiral perturbation theory in the meson sector at order $E^6$. In the terminology of the external field technique, the two--loop graphs so generated are of the sunset type. We discuss the evaluation of several of these in the case where the masses of the particles running in the loops are equal. In particular, we present integral representations that are suitable for the evaluation of diagrams in kinematical regions where branch points and cuts are present., 28 pages, LaTeX, 5 figures embedded with epsf.sty

A dispersion framework, appropriate for discussing the low-energy pion-nucleon interaction, is reviewed. Sensitivity of the isoscalar D-amplitude at the unphysical Cheng-Dashen point to input from different phase shift analyses and low-energy experiments is discussed., 6 pages, no figures

This is the summary of the working group on $����$ and $��$N interactions of the Chiral Dynamics Workshop in Mainz, September 1-5, 1997. Each talk is represented by an extended one page abstract. Some additional remarks by the convenors are added, 20 pp, LaTeX2e, uses epsf, 1 fig

We evaluate analytically the elastic $����$ scattering amplitude to two loops in chiral perturbation theory and give numerical values for the two $S$--wave scattering lengths and for the phase shift difference $��_0^0-��_1^1$., 10 pages, LaTeX, uses epsfig.sty, one postscript picture included. Full postscript file available at http/www.nordita.dk/locinfo/preprints/95077.ps.gz