Threshold Behaviour of Meson-Nucleon-$S_{11}$(1535) Vertexfunctions and Determination of the $S_{11}$(1535) Mixing Angle

Abstract

A new method for the determination of the spin-1/2-3/2-mixing angle and the range parameter of the quarkmodel wavefunction of the resonance $S_{11}^{-}(1535)$ is presented. The method ist based on a quantitative calculation of the total cross section of $pp\to pp\eta$ at threshold. The quantitative on-shell treatment of ISI and FSI is discussed.

Comments: 4 pages, no figures; Proceeding of the Eighth Int. Symposium on "Meson-Nucleon Physics and the Structure of the Nucleon", August 15-21, 1999, Zuoz; corrected typos