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

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