Kaon photoproduction on the nucleon: overview of some applications

Some applications of the elementary kaon photoproduction process are discussed: the investigation of missing resonances in the p(gamma,K+)Lambda channel, the role of the P_{13}(1720) state in the p(gamma,K0)Sigma+ channel, and the calculation of the Gerasimov-Drell-Hearn sum rule. For the latter, we present an extension of our previous study to higher energies.Comment: 3 pages, contribution to FB2000 (Taiwan) March 2000, to be published in Nucl. Phys.

Electromagnetic K+ production on the deuteron with hyperon recoil polarization

Photo- and electroproduction processes of K+ on the deuteron are investigated theoretically. Modern hyperon-nucleon forces as well as an updated kaon production operator on the nucleon are used. Sizable effects of the hyperon-nucleon final state interaction are seen in various observables. Especially the photoproduction double polarization observable C_z is shown to provide a handle to distinguish different hyperon-nucleon force models.Comment: 4 pages, 7 eps-figures, talk given at the VII International Conference on Hypernuclear and Strange Particle Physics, Torino, Italy, October 23-27, 2000, to appear in the proceedings (Nucl. Phys. A

Preserving the gauge invariance of meson production currents in the presence of explicit final-state interactions

A comprehensive formalism is developed to preserve the gauge invariance of currents describing the photo- or electroproduction of mesons off the nucleon when the final-state interactions of mesons and nucleons is taken into account explicitly. Replacing exchange currents by auxiliary currents, it is found that all contributions due to explicit final-state interactions are purely transverse and do not contain a Kroll-Ruderman-type contact current. The relation of the present formulation to tree-level-type prescriptions is shown.Comment: 6 pages, 2 figures; published versio

Inclusive K+K^+ and exclusive K+YK^+Y photoproduction on the deuteron: Λ\Lambda- and Σ\Sigma-threshold phenomena

Inclusive $K^+$ and exclusive $K^+Y$ photoproduction on the deuteron are investigated theoretically. Modern hyperon-nucleon forces and a recently updated kaon photoproduction operator for the $\gamma +N\to K^++Y$ process are used. Sizable effects of the hyperon-nucleon final state interaction are found near the $K^+\Lambda N$ and $K^+\Sigma N$ thresholds in the inclusive reaction. Angular distributions for the exclusive process show clear $YN$ final state interaction effects in certain kinematic regions. Precise data especially for the inclusive process around the $K^+\Sigma N$ threshold would help to clarify the strength and property of the $\Lambda N-\Sigma N$ interaction.Comment: 14 pages, 10 figure