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

A dynamical coupled-channels formalism for processes pi N -> KY and gamma N -> KY is presented that provides a comprehensive investigation of recent data on the gamma p -> K+Lambda reaction. The nonresonant interactions within the subspace KY circle plus pi N 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 gamma N ->pi N amplitudes are input and only the parameters associated with the KY channel are determined by performing chi(2) fits to all of the available data for pi(-)p -> K-degrees Lambda,K-degrees Sigma(degrees), and gamma p -> K+Lambda. Good agreement between our models and those data are obtained. In the fits to pi N -> 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 gamma p -> K+Lambda parameters, ranges compatible with broken SU(6) circle times O(3) symmetry are imposed. The main reaction mechanisms in K+Lambda photoproduction are singled out and issues related to newly suggested resonances S-11,P-13, and D-13 are studied. Results illustrating the importance of using a coupled-channels treatment are reported. Meson cloud effects on the gamma N -> N-* transitions are also discussed.