1998/11/02 by F. Kleefeld, M. Dillig
Physics and Astronomy · #nucl-th
published as Proc. 8th Int. Conf. on the Structure of Baryons (Baryons '98), 22-26.9.1998, Bonn, Germany, p. 613-616 (Eds. D.W. Menze, B. Metsch, ISBN 981-02-3865-7, (c) 1999 by World Scientific Publishing Co. Pte. Ltd.) · 4 pages; contribution to BARYONS98, Bonn, Germany, September 1998
arxiv created 1998/11/02 · arxiv updated 2009/12/01
We present some details of our recent theoretical investigations on the total cross section of the reactions pp→ pp π0, pp→ pp η and pp→ pΛK+ at threshold. Applying standard nonrelativistic perturbation theory within the framework of meson exchange models (MEC) to all of the investigated processes we observe that theory is still far--off from a quantitative understanding of the existing data, although the qualitative behaviour of the threshold cross sections can be reproduced. The often quoted η2--dependence of the pp→ pp π0 cross section at threshold is due to a calculational mistake of Koltun and Reitan (1966) and not based on theoretical grounds, where threebody phasespace behaviour would yield η4, which can be affected by final state and short range effects. To respect the high momentum transfers for pp→ pp η and pp→ pΛK+ relativistic models were developed. Hereby the η--production still is based on MEC, while the K+ production was investigated in the quark-gluon-picture based on the Bethe--Salpeter formalism.