Dynamical coupled-channels approach to hadronic and electromagnetic kaon-hyperon production on the proton

A dynamical coupled-channels formalism for processes πN→KY and γN→KY is presented that provides a comprehensive investigation of recent data on the γp→K⁺Λ reaction. The nonresonant interactions within the subspace KY⊕πN are derived from effective Lagrangians, using a unitary transformation method. The calculations of photoproduction amplitudes are simplified by casting the coupled-channels equations into a form such that the empirical γN→πN amplitudes are input and only the parameters associated with the KY channel are determined by performing χ² fits to all of the available data for π^-p→K^°Λ,K^°Σ^°, and γp→K⁺Λ. Good agreement between our models and those data are obtained. In the fits to πN→KY channels, most of the parameters are constrained within ±20% of the values given by the Particle Data Group and/or quark model predictions, whereas for γp→K⁺Λ parameters, ranges compatible with broken SU(6) ⊗ O(3) symmetry are imposed. The main reaction mechanisms in K⁺Λ photoproduction are singled out and issues related to newly suggested resonances S₁₁,P₁₃, and D₁₃ are studied. Results illustrating the importance of using a coupled-channels treatment are reported. Meson cloud effects on the γN→N^* transitions are also discussed.