Dynamics of strangeness production in the near threshold nucleonnucleon collisions.pdfVIP

Dynamics of strangeness production in the near threshold nucleon-nucleon collisions1 Radhey Shyama 4 a Saha Institute of Nuclear Physics, Calcutta, India and 0 0 Department of Radiation Sciences, Uppsala University, Uppsala, Sweden 2 n u J Abstract: We investigate the associated strangeness production reactions + 0 + 7 pp → pΛK and pp → p Σ K within an effective Lagrangian model. The 2 initial interaction between the two nucleons is modeled by the exchange of π , ρ, ω , and σ mesons and the strangeness production proceeds via exci- 1 tations of N ∗ (1650), N ∗ (1710), and N ∗ (1720) baryonic resonance states. v 7 The parameters of the model at the nucleon-nucleon-meson vertices are 9 determined by fitting the elastic nucleon-nucleon scattering with an effec- 2 tive interaction based on the exchange of these four mesons, while those 6 at the resonance vertices are calculated from the known decay widths of 0 the resonances and from the vector meson dominance model. Experimen- 4 0 tal data taken recently by the COSY-11 collaboration are described well / by this approach. The one-pion-exchange diagram dominates the produc- h tion process at both higher and lower beam energies. The excitation of p ∗ - the N (1650) resonance contributes predominantly to both the production p channels at near threshold energies. Our model with final state in