Photoproduction ofKMesons in Hydrogen near Threshold

The total cross sections near threshold of the three processes: $\gamma +p\to {\Lambda }^0+K^{+}, {\Sigma }^0+K^{+}, {\Sigma }^{+}+K^0$, have been calculated as a function of the incident photon energy in the laboratory system under the assumptions that the hyperons have spin ${\mathrm{½}}^{+}$ with positive anomalous magnetic moments and that the $K$ meson has spin 0± and is coupled to the baryon field by direct Yukawa interaction. A pseudoscalar $K$ meson gives a steep increase of the cross section for neutral production and at the same time gives a large $\frac{K^0}{K^{+}}$ production ratio compared to that for a scalar $K$ meson.