Electromagnetic production of kaons

Employing diagrammatic techniques, a model for the reactions ${}_{}{}^1{}_{}{}^{}\mathrm{H}(\gamma ,K^{+})\Lambda$ and ${}_{}{}^1{}_{}{}^{}\mathrm{H}(e,e^{\prime }{K}^{+})\Lambda$ is derived with the coupling constants being determined phenomenologically by a least-squares fit to the available data. We find a strong sensitivity of the photoproduction process to $t$-channel exchange terms. The inclusion of the kaon resonance $Q1\left(1280\mathrm{} \mathrm{MeV}\right)$ brings the dominant $K\Lambda N$ coupling constant in agreement with predictions from the analysis of $\mathrm{Kp}$ scattering data. An excellent fit to the electroproduction data confirms former measurements of the kaon radius.