THRESHOLD KAON PHOTOPRODUCTION AND ELECTROPRODUCTION IN SU(3) BARYON CHIRAL PERTURBATION-THEORY

We calculate the processes gamma p --> K-0 Sigma(+), K(+)Sigma(0), K()Lambda in three flavor heavy baryon chital perturbation theory to one : loop. Some low-energy constants are fixed from single baryon propert ies while others are estimated by means of resonance saturation In add ition, the shapes of the differential cross sections for K+ production are used to fix the range for two oi the constants. The predicted tot al cross sections are comparable with the few existing data points in the threshold region. The angular dependences of the recoil polarizati on of the Lambda and Sigma(0) show most features of the ones measured at ELSA. We also predict the isovector charge radius of the Sigma(+), [r(V)(2)](Sigma+) = (0.30 +/- 0.03) fm(2).